Assertion in Erasure.adaptToType

[scf37]

Compiler version

3.1.3

Minimized code

object Test {
  trait Transaction
  type Transactional[T] = (t: Transaction) ?=> T

  def ff(x: Int): Transactional[Int] = {
    summon[Transaction]
    x
  }

  def fff(x: Int): Transactional[Int] = {
    summon[Transaction]
    ff(x)
    ???
  }

}

Output (click arrow to expand)

java.lang.AssertionError: assertion failed
	at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:11)
	at dotty.tools.dotc.transform.Erasure$Boxing$.adaptToType(Erasure.scala:388)
	at dotty.tools.dotc.transform.Erasure$Typer.adapt(Erasure.scala:1053)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2960)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2964)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:3013)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3036)
	at dotty.tools.dotc.transform.Erasure$Typer.typedStats(Erasure.scala:1041)
	at dotty.tools.dotc.typer.Typer.typedBlockStats(Typer.scala:1067)
	at dotty.tools.dotc.typer.Typer.typedBlock(Typer.scala:1071)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2840)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2895)
	at dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:123)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2960)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2964)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3080)
	at dotty.tools.dotc.typer.Typer.$anonfun$47(Typer.scala:2278)
	at dotty.tools.dotc.typer.PrepareInlineable$.dropInlineIfError(PrepareInlineable.scala:248)
	at dotty.tools.dotc.typer.Typer.typedDefDef(Typer.scala:2278)
	at dotty.tools.dotc.transform.Erasure$Typer.typedDefDef(Erasure.scala:943)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2808)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2894)
	at dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:123)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2960)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2964)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2986)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3036)
	at dotty.tools.dotc.transform.Erasure$Typer.typedStats(Erasure.scala:1041)
	at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:2476)
	at dotty.tools.dotc.transform.Erasure$Typer.typedClassDef(Erasure.scala:1031)
	at dotty.tools.dotc.typer.Typer.typedTypeOrClassDef$1(Typer.scala:2820)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2824)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2894)
	at dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:123)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2960)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2964)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2986)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:3036)
	at dotty.tools.dotc.transform.Erasure$Typer.typedStats(Erasure.scala:1041)
	at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:2603)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2865)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2895)
	at dotty.tools.dotc.typer.ReTyper.typedUnadapted(ReTyper.scala:123)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2960)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2964)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:3080)
	at dotty.tools.dotc.transform.Erasure.run(Erasure.scala:144)
	at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:311)
	at scala.collection.immutable.List.map(List.scala:246)
	at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:312)
	at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:225)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1328)
	at dotty.tools.dotc.Run.runPhases$1(Run.scala:236)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:244)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:253)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:68)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:253)
	at dotty.tools.dotc.Run.compileSources(Run.scala:186)
	at dotty.tools.dotc.Run.compile(Run.scala:170)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:35)
	at dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:88)
	at dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
	at sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
	at org.jetbrains.jps.incremental.scala.local.IdeaIncrementalCompiler.compile(IdeaIncrementalCompiler.scala:57)
	at org.jetbrains.jps.incremental.scala.local.LocalServer.doCompile(LocalServer.scala:52)
	at org.jetbrains.jps.incremental.scala.local.LocalServer.compile(LocalServer.scala:30)
	at org.jetbrains.jps.incremental.scala.remote.Main$.compileLogic(Main.scala:207)
	at org.jetbrains.jps.incremental.scala.remote.Main$.$anonfun$handleCommand$1(Main.scala:190)
	at org.jetbrains.jps.incremental.scala.remote.Main$.decorated$1(Main.scala:180)
	at org.jetbrains.jps.incremental.scala.remote.Main$.handleCommand(Main.scala:187)
	at org.jetbrains.jps.incremental.scala.remote.Main$.serverLogic(Main.scala:163)
	at org.jetbrains.jps.incremental.scala.remote.Main$.nailMain(Main.scala:103)
	at org.jetbrains.jps.incremental.scala.remote.Main.nailMain(Main.scala)
	at jdk.internal.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at com.martiansoftware.nailgun.NGSession.run(NGSession.java:319)

[scf37]

Also fails:

  def fff(x: Int): Transactional[Int] = {
    ff(x)
    42
  }

Also:

  def fff(x: Int): Transactional[Int] = {
    ff(x)  
   // Found:    Test.Transactional[Int]
   //Required: Int
   // ff(x)
  }

[scf37]

This is regression, worked in 3.1.1, fails since 3.1.2

[odersky]

I note it works if we write type Transactional[T] = Transaction ?=> T. It's the dependent function type (t: Transaction) ?=> T that makes it fail.

[scf37]

Actually i've seen it as "finally Scala supports readable function types" :-)