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null used as prefix of type application during implicit search #18695

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Katrix opened this issue Oct 13, 2023 · 4 comments
Closed

null used as prefix of type application during implicit search #18695

Katrix opened this issue Oct 13, 2023 · 4 comments
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@odersky
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area:implicits related to implicits area:typer itype:bug itype:crash

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@Katrix
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Katrix commented Oct 13, 2023

Encountered this when I got the priorization of implicits slightly wrong. Swapping fromTuple and tupleFromMirrorAndLength makes it work fine in this case. Not actually sure what the bug is here. This is as small as I could minimize it

Compiler version

3.3.1

If you're not sure what version you're using, run print scalaVersion from sbt
(if you're running scalac manually, use scalac -version instead).

Minimized code

import scala.annotation.{tailrec, unused}
import scala.deriving.Mirror
import scala.quoted.*

trait TypeLength[A] {
  type Length <: Int
  def length: Length
}
object TypeLength extends TypeLengthLowPriority:
  type Aux[A, Length0 <: Int] = TypeLength[A] {
    type Length = Length0
  }

  transparent inline given fromMirror[A](using m: Mirror.Of[A]): TypeLength[A] =
    ${ macroImpl[A, m.MirroredElemTypes] }

  @tailrec
  private def typesOfTuple(
      using q: Quotes
  )(tpe: q.reflect.TypeRepr, acc: List[q.reflect.TypeRepr]): List[q.reflect.TypeRepr] =
    import q.reflect.*
    val cons = Symbol.classSymbol("scala.*:")
    tpe.widenTermRefByName.dealias match
      case AppliedType(fn, tpes) if defn.isTupleClass(fn.typeSymbol) =>
        tpes.reverse_:::(acc)
      case AppliedType(tp, List(headType, tailType)) if tp.derivesFrom(cons) =>
        typesOfTuple(tailType, headType :: acc)
      case tpe =>
        if tpe.derivesFrom(Symbol.classSymbol("scala.EmptyTuple")) then acc.reverse
        else report.errorAndAbort(s"Unknown type encountered in tuple ${tpe.show}")

  def macroImpl[A: Type, T <: Tuple: scala.quoted.Type](
      using q: scala.quoted.Quotes
  ): scala.quoted.Expr[TypeLength[A]] =
    import q.reflect.*
    val l = typesOfTuple(TypeRepr.of[T], Nil).length
    ConstantType(IntConstant(l)).asType match
      case '[lt] =>
        val le = Expr[Int](l).asExprOf[lt & Int]
        '{
          val r: TypeLength.Aux[A, lt & Int] = new TypeLength[A] {
            type Length = lt & Int
            val length: Length = ${ le }
          }
          r
        }

  transparent inline given fromTuple[T <: Tuple]: TypeLength[T] =
    ${ macroImpl[T, T] }

trait TypeLengthLowPriority:
  self: TypeLength.type =>
  given tupleFromMirrorAndLength[A, T <: Tuple](
      using @unused m: Mirror.Of[A] { type MirroredElemTypes = T },
      length: TypeLength[A]
  ): TypeLength.Aux[T, length.Length] = length.asInstanceOf[TypeLength.Aux[T, length.Length]]

trait HKDSumGeneric[A]
object HKDSumGeneric:
  type NotZero[N <: Int] = N match
    case 0 => false
    case _ => true

  transparent inline given derived[A](using m: Mirror.SumOf[A], typeLength: TypeLength[A])(
      using NotZero[typeLength.Length] =:= true
  ): HKDSumGeneric[A] =
    derivedImpl[A, m.MirroredElemTypes, m.MirroredLabel]

  def derivedImpl[A, ElemTypes <: Tuple, Label <: String](
      using m: Mirror.SumOf[A] {
        type MirroredElemTypes = ElemTypes; type MirroredLabel = Label;
      },
      typeLength: TypeLength[ElemTypes],
      nz: NotZero[typeLength.Length] =:= true
  ): HKDSumGeneric[A] = ???

Output (click arrow to expand)

java.lang.AssertionError: assertion failed while typechecking D:\DevProjects\Stable\perspective\dotty\derivation\src\main\scala\perspective\derivation\test1.scala
[info] exception occurred while typechecking D:\DevProjects\Stable\perspective\dotty\derivation\src\main\scala\perspective\derivation\test1.scala
[info]
[info]   exception occurred while compiling List(D:\DevProjects\Stable\perspective\dotty\derivation\src\main\scala\perspective\derivation\test1.scala)
[info]
[info]   An unhandled exception was thrown in the compiler.
[info]   Please file a crash report here:
[info]   https://github.com/lampepfl/dotty/issues/new/choose
[info]
[info]      while compiling: <no file>
[info]         during phase: <no phase>
[info]                 mode: Mode(ImplicitsEnabled)
[info]      library version: version 2.13.10
[info]     compiler version: version 3.3.1
[info]             settings: -Ykind-projector "" -bootclasspath C:\Users\katri\AppData\Local\Coursier\Cache\v1\https\repo1.maven.org\maven2\org\scala-lang\scala3-library_3\3.3.1\scala3-library_3-3.3.1.jar;C:\Users\katri\AppData\Local\Coursier\Cache\v1\https\repo1.maven.org\maven2\org\scala-lang\scala-library\2.13.10\scala-library-2.13.10.jar -classpath D:\DevProjects\Stable\perspective\dotty\derivation\target\scala-3.3.1\classes;D:\DevProjects\Stable\perspective\dotty\perspective\target\scala-3.3.1\classes;C:\Users\katri\AppData\Local\Coursier\Cache\v1\https\repo1.maven.org\maven2\org\typelevel\cats-core_3\2.8.0\cats-core_3-2.8.0.jar;C:\Users\katri\AppData\Local\Coursier\Cache\v1\https\repo1.maven.org\maven2\org\typelevel\cats-kernel_3\2.8.0\cats-kernel_3-2.8.0.jar -d D:\DevProjects\Stable\perspective\dotty\derivation\target\scala-3.3.1\classes -feature true
[info]
[info]                 tree: EmptyTree
[info]        tree position: :<unknown>
[info]            tree type: <notype>
[info]               symbol: val <none>
[info]            call site: package <root> in module class <root>
[info]
[info]   == Source file context for tree position ==
[info]
[error] ## Exception when compiling 11 sources to D:\DevProjects\Stable\perspective\dotty\derivation\target\scala-3.3.1\classes
[error] java.lang.AssertionError: assertion failed
[error] scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:11)
[error] dotty.tools.dotc.ast.tpd$.TypeApply(tpd.scala:60)
[error] dotty.tools.dotc.ast.tpd$TreeOps$.appliedToTypeTrees$extension(tpd.scala:985)
[error] dotty.tools.dotc.typer.Typer.adapt1(Typer.scala:4255)
[error] dotty.tools.dotc.typer.Typer.adapt(Typer.scala:3587)
[error] dotty.tools.dotc.typer.ProtoTypes$FunProto.typedArg(ProtoTypes.scala:497)
[error] dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:897)
[error] dotty.tools.dotc.typer.Applications$ApplyToUntyped.typedArg(Applications.scala:897)
[error] dotty.tools.dotc.typer.Applications$Application.addTyped$1(Applications.scala:589)
[error] dotty.tools.dotc.typer.Applications$Application.matchArgs(Applications.scala:653)
[error] dotty.tools.dotc.typer.Applications$Application.init(Applications.scala:492)
[error] dotty.tools.dotc.typer.Applications$TypedApply.<init>(Applications.scala:779)
[error] dotty.tools.dotc.typer.Applications$ApplyToUntyped.<init>(Applications.scala:896)
[error] dotty.tools.dotc.typer.Applications.ApplyTo(Applications.scala:1126)
[error] dotty.tools.dotc.typer.Applications.ApplyTo$(Applications.scala:352)
[error] dotty.tools.dotc.typer.Typer.ApplyTo(Typer.scala:116)
[error] dotty.tools.dotc.typer.Applications.simpleApply$1(Applications.scala:969)
[error] dotty.tools.dotc.typer.Applications.realApply$1$$anonfun$2(Applications.scala:1052)
[error] dotty.tools.dotc.typer.Typer.tryEither(Typer.scala:3324)
[error] dotty.tools.dotc.typer.Applications.realApply$1(Applications.scala:1063)
[error] dotty.tools.dotc.typer.Applications.typedApply(Applications.scala:1101)
[error] dotty.tools.dotc.typer.Applications.typedApply$(Applications.scala:352)
[error] dotty.tools.dotc.typer.Typer.typedApply(Typer.scala:116)
[error] dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:3048)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3112)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3184)
[error] dotty.tools.dotc.typer.Implicits.tryConversion$1(Implicits.scala:1136)
[error] dotty.tools.dotc.typer.Implicits.typedImplicit(Implicits.scala:1167)
[error] dotty.tools.dotc.typer.Implicits.typedImplicit$(Implicits.scala:818)
[error] dotty.tools.dotc.typer.Typer.typedImplicit(Typer.scala:116)
[error] dotty.tools.dotc.typer.Implicits$ImplicitSearch.tryImplicit(Implicits.scala:1242)
[error] dotty.tools.dotc.typer.Implicits$ImplicitSearch.rank$1(Implicits.scala:1341)
[error] dotty.tools.dotc.typer.Implicits$ImplicitSearch.searchImplicit(Implicits.scala:1511)
[error] dotty.tools.dotc.typer.Implicits$ImplicitSearch.searchImplicit(Implicits.scala:1539)
[error] dotty.tools.dotc.typer.Implicits$ImplicitSearch.searchImplicit(Implicits.scala:1547)
[error] dotty.tools.dotc.typer.Implicits$ImplicitSearch.bestImplicit(Implicits.scala:1572)
[error] dotty.tools.dotc.typer.Implicits.inferImplicit(Implicits.scala:1060)
[error] dotty.tools.dotc.typer.Implicits.inferImplicit$(Implicits.scala:818)
[error] dotty.tools.dotc.typer.Typer.inferImplicit(Typer.scala:116)
[error] dotty.tools.dotc.typer.Implicits.inferView(Implicits.scala:856)
[error] dotty.tools.dotc.typer.Implicits.inferView$(Implicits.scala:818)
[error] dotty.tools.dotc.typer.Typer.inferView(Typer.scala:116)
[error] dotty.tools.dotc.typer.Implicits.viewExists(Implicits.scala:831)
[error] dotty.tools.dotc.typer.Implicits.viewExists$(Implicits.scala:818)
[error] dotty.tools.dotc.typer.Typer.viewExists(Typer.scala:116)
[error] dotty.tools.dotc.typer.Implicits.ignoredConvertibleImplicits$1$$anonfun$3(Implicits.scala:960)
[error] scala.collection.Iterator$$anon$6.hasNext(Iterator.scala:479)
[error] scala.collection.Iterator.isEmpty(Iterator.scala:466)
[error] scala.collection.Iterator.isEmpty$(Iterator.scala:466)
[error] scala.collection.AbstractIterator.isEmpty(Iterator.scala:1300)
[error] scala.collection.View$Filter.isEmpty(View.scala:146)
[error] scala.collection.IterableOnceOps.nonEmpty(IterableOnce.scala:833)
[error] scala.collection.IterableOnceOps.nonEmpty$(IterableOnce.scala:833)
[error] scala.collection.AbstractIterable.nonEmpty(Iterable.scala:933)
[error] dotty.tools.dotc.reporting.MissingImplicitArgument.noChainConversionsNote$1(messages.scala:2838)
[error] dotty.tools.dotc.reporting.MissingImplicitArgument.msgPostscript$$anonfun$4(messages.scala:2846)
[error] scala.Option.orElse(Option.scala:477)
[error] dotty.tools.dotc.reporting.MissingImplicitArgument.msgPostscript(messages.scala:2846)
[error] dotty.tools.dotc.reporting.Message.message$$anonfun$1(Message.scala:345)
[error] dotty.tools.dotc.reporting.Message.inMessageContext(Message.scala:341)
[error] dotty.tools.dotc.reporting.Message.message(Message.scala:345)
[error] dotty.tools.dotc.reporting.Message.isNonSensical(Message.scala:322)
[error] dotty.tools.dotc.reporting.HideNonSensicalMessages.isHidden(HideNonSensicalMessages.scala:16)
[error] dotty.tools.dotc.reporting.HideNonSensicalMessages.isHidden$(HideNonSensicalMessages.scala:10)
[error] dotty.tools.dotc.reporting.AbstractReporter.isHidden(AbstractReporter.scala:8)
[error] dotty.tools.dotc.reporting.Reporter.issueUnconfigured(Reporter.scala:156)
[error] dotty.tools.dotc.reporting.Reporter.go$1(Reporter.scala:181)
[error] dotty.tools.dotc.reporting.Reporter.issueIfNotSuppressed(Reporter.scala:200)
[error] dotty.tools.dotc.reporting.Reporter.report(Reporter.scala:203)
[error] dotty.tools.dotc.report$.error(report.scala:68)
[error] dotty.tools.dotc.typer.Typer.issueErrors$1$$anonfun$1(Typer.scala:3808)
[error] scala.runtime.function.JProcedure3.apply(JProcedure3.java:15)
[error] scala.runtime.function.JProcedure3.apply(JProcedure3.java:10)
[error] scala.collection.LazyZip3.foreach(LazyZipOps.scala:248)
[error] dotty.tools.dotc.typer.Typer.issueErrors$1(Typer.scala:3810)
[error] dotty.tools.dotc.typer.Typer.addImplicitArgs$1(Typer.scala:3832)
[error] dotty.tools.dotc.typer.Typer.adaptNoArgsImplicitMethod$1(Typer.scala:3849)
[error] dotty.tools.dotc.typer.Typer.adaptNoArgs$1(Typer.scala:4038)
[error] dotty.tools.dotc.typer.Typer.adapt1(Typer.scala:4268)
[error] dotty.tools.dotc.typer.Typer.adapt(Typer.scala:3587)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3184)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3188)
[error] dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3300)
[error] dotty.tools.dotc.typer.Typer.$anonfun$57(Typer.scala:2486)
[error] dotty.tools.dotc.inlines.PrepareInlineable$.dropInlineIfError(PrepareInlineable.scala:243)
[error] dotty.tools.dotc.typer.Typer.typedDefDef(Typer.scala:2486)
[error] dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:3024)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3111)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3184)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3188)
[error] dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3210)
[error] dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3256)
[error] dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2669)
[error] dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:3036)
[error] dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:3040)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3111)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3184)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3188)
[error] dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3210)
[error] dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3256)
[error] dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2812)
[error] dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:3081)
[error] dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:3112)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3184)
[error] dotty.tools.dotc.typer.Typer.typed(Typer.scala:3188)
[error] dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3300)
[error] dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$1(TyperPhase.scala:44)
[error] dotty.tools.dotc.typer.TyperPhase.typeCheck$$anonfun$adapted$1(TyperPhase.scala:54)
[error] scala.Function0.apply$mcV$sp(Function0.scala:42)
[error] dotty.tools.dotc.core.Phases$Phase.monitor(Phases.scala:440)
[error] dotty.tools.dotc.typer.TyperPhase.typeCheck(TyperPhase.scala:54)
[error] dotty.tools.dotc.typer.TyperPhase.runOn$$anonfun$3(TyperPhase.scala:88)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:333)
[error] dotty.tools.dotc.typer.TyperPhase.runOn(TyperPhase.scala:88)
[error] dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:246)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1321)
[error] dotty.tools.dotc.Run.runPhases$1(Run.scala:262)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:270)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:279)
[error] dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:67)
[error] dotty.tools.dotc.Run.compileUnits(Run.scala:279)
[error] dotty.tools.dotc.Run.compileSources(Run.scala:194)
[error] dotty.tools.dotc.Run.compile(Run.scala:179)
[error] dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
[error] dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:88)
[error] dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
[error] sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:193)
[error] scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
[error] sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:248)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:183)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163)
[error] sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:211)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:179)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:177)
[error] sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:463)
[error] sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
[error] sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263)
[error] sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:418)
[error] sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:506)
[error] sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:405)
[error] sbt.internal.inc.Incremental$.apply(Incremental.scala:171)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:488)
[error] sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:425)
[error] sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
[error] sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2364)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2314)
[error] sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:30)
[error] sbt.internal.io.Retry$.apply(Retry.scala:46)
[error] sbt.internal.io.Retry$.apply(Retry.scala:28)
[error] sbt.internal.io.Retry$.apply(Retry.scala:23)
[error] sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:30)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2312)
[error] scala.Function1.$anonfun$compose$1(Function1.scala:49)
[error] sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:62)
[error] sbt.std.Transform$$anon$4.work(Transform.scala:68)
[error] sbt.Execute.$anonfun$submit$2(Execute.scala:282)
[error] sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:23)
[error] sbt.Execute.work(Execute.scala:291)
[error] sbt.Execute.$anonfun$submit$1(Execute.scala:282)
[error] sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
[error] sbt.CompletionService$$anon$2.call(CompletionService.scala:64)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
[error] java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
[error] java.base/java.lang.Thread.run(Thread.java:833)
@Katrix Katrix added itype:bug itype:crash stat:needs triage Every issue needs to have an "area" and "itype" label labels Oct 13, 2023
@nicolasstucki
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With the improved error message in #18700 we get the following failure

Exception in thread "main" java.lang.AssertionError: assertion failed: Illegal TypeApply function prefix: Literal(Constant(null))
        at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
        at dotty.tools.dotc.ast.tpd$.TypeApply(tpd.scala:61)
        at dotty.tools.dotc.ast.tpd$TreeOps$.appliedToTypeTrees$extension(tpd.scala:993)

The macro is attempting to create the AST null[A].

@nicolasstucki
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Minimized
trait Foo { type Num <: Int }
given derived[A](using foo: Foo): Any = derivedImpl(foo)
def derivedImpl(foo: Foo)(using bar: foo.Num =:= Int): Any = ???

@nicolasstucki nicolasstucki added area:implicits related to implicits area:typer and removed stat:needs triage Every issue needs to have an "area" and "itype" label labels Oct 16, 2023
@nicolasstucki nicolasstucki changed the title Crash when calling macro producing constant type in inline function null used as prefix of type application during implicit search Oct 16, 2023
@smarter
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smarter commented Oct 24, 2023

The null comes from dummyTreeOfType in https://github.com/lampepfl/dotty/blob/15033c7ac8be33a1b94226da3cca3922b53066ce/compiler/src/dotty/tools/dotc/typer/Implicits.scala#L855
Can we simply add a check beforehand that does !from.widen.isInstanceOf[MethodicType] ?

@dwijnand
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dwijnand commented Oct 24, 2023 •
edited
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We have. #18719

odersky added a commit to dotty-staging/dotty that referenced this issue Oct 25, 2023
@odersky
Avoid crash arising from trying to find conversions from polymorphic …
f995a8c 
…singleton types

This is an alternative fix for scala#18695, which already got fixed in a different way by scala#18719.
This PR adds the actual tests, and leaves in the fix as a defensive measure in case the situation
arises by some other means than the one foxed in scala#18719.
@odersky odersky mentioned this issue Oct 25, 2023
Merged
WojciechMazur pushed a commit that referenced this issue Jun 22, 2024
@odersky @WojciechMazur
Avoid crash arising from trying to find conversions from polymorphic …
46fc93d 
…singleton types

This is an alternative fix for #18695, which already got fixed in a different way by #18719.
This PR adds the actual tests, and leaves in the fix as a defensive measure in case the situation
arises by some other means than the one foxed in #18719.

[Cherry-picked f995a8c]
WojciechMazur pushed a commit that referenced this issue Jun 23, 2024
@odersky @WojciechMazur
Avoid crash arising from trying to find conversions from polymorphic …
e90d376 
…singleton types

This is an alternative fix for #18695, which already got fixed in a different way by #18719.
This PR adds the actual tests, and leaves in the fix as a defensive measure in case the situation
arises by some other means than the one foxed in #18719.

[Cherry-picked f995a8c]
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