crash on compilable code: assertion failed: failure to construct path from method ...

[helloqirun]

scalac can compile it but dotc crashes.

$ cat abc.scala

object test {
  def f[a](x: a) = {
    def print = (x)
    class A {
      {
        class B { def h = print }
        new B
      }
    }
  }
}

$ dotc abc.scala

exception while transforming print() of class class dotty.tools.dotc.ast.Trees$Apply # 228
exception while transforming def h(): Object = print() of class class dotty.tools.dotc.ast.Trees$DefDef # 229
exception while transforming  extends Object {
  def <init>(): Unit =
    {
      super()
      ()
    }
  def h(): Object = print()
} of class class dotty.tools.dotc.ast.Trees$Template # 253
exception while transforming private class B extends Object {
  def <init>(): Unit =
    {
      super()
      ()
    }
  def h(): Object = print()
} of class class dotty.tools.dotc.ast.Trees$TypeDef # 254
exception while transforming {
  private class B extends Object {
    def <init>(): Unit =
      {
        super()
        ()
      }
    def h(): Object = print()
  }
  new B(): Object
} of class class dotty.tools.dotc.ast.Trees$Block # 255
exception while transforming {
  super()
  {
    private class B extends Object {
      def <init>(): Unit =
        {
          super()
          ()
        }
      def h(): Object = print()
    }
    new B(): Object
  }
  ()
} of class class dotty.tools.dotc.ast.Trees$Block # 264
exception while transforming def <init>(): Unit =
  {
    super()
    {
      private class B extends Object {
        def <init>(): Unit =
          {
            super()
            ()
          }
        def h(): Object = print()
      }
      new B(): Object
    }
    ()
  } of class class dotty.tools.dotc.ast.Trees$DefDef # 265
exception while transforming  extends Object {
  def <init>(): Unit =
    {
      super()
      {
        private class B extends Object {
          def <init>(): Unit =
            {
              super()
              ()
            }
          def h(): Object = print()
        }
        new B(): Object
      }
      ()
    }
} of class class dotty.tools.dotc.ast.Trees$Template # 266
exception while transforming private class A extends Object {
  def <init>(): Unit =
    {
      super()
      {
        private class B extends Object {
          def <init>(): Unit =
            {
              super()
              ()
            }
          def h(): Object = print()
        }
        new B(): Object
      }
      ()
    }
} of class class dotty.tools.dotc.ast.Trees$TypeDef # 267
exception while transforming {
  private def print(): Object = x
  private class A extends Object {
    def <init>(): Unit =
      {
        super()
        {
          private class B extends Object {
            def <init>(): Unit =
              {
                super()
                ()
              }
            def h(): Object = print()
          }
          new B(): Object
        }
        ()
      }
  }
  ()
} of class class dotty.tools.dotc.ast.Trees$Block # 268
exception while transforming def f(x: Object): Unit =
  {
    private def print(): Object = x
    private class A extends Object {
      def <init>(): Unit =
        {
          super()
          {
            private class B extends Object {
              def <init>(): Unit =
                {
                  super()
                  ()
                }
              def h(): Object = print()
            }
            new B(): Object
          }
          ()
        }
    }
    ()
  } of class class dotty.tools.dotc.ast.Trees$DefDef # 269
exception while transforming  extends Object {
  def <init>(): Unit =
    {
      super()
      ()
    }
  def f(x: Object): Unit =
    {
      private def print(): Object = x
      private class A extends Object {
        def <init>(): Unit =
          {
            super()
            {
              private class B extends Object {
                def <init>(): Unit =
                  {
                    super()
                    ()
                  }
                def h(): Object = print()
              }
              new B(): Object
            }
            ()
          }
      }
      ()
    }
} of class class dotty.tools.dotc.ast.Trees$Template # 280
exception while transforming @scala.annotation.internal.SourceFile("abc.scala") final module class test$ extends Object {
  def <init>(): Unit =
    {
      super()
      ()
    }
  def f(x: Object): Unit =
    {
      private def print(): Object = x
      private class A extends Object {
        def <init>(): Unit =
          {
            super()
            {
              private class B extends Object {
                def <init>(): Unit =
                  {
                    super()
                    ()
                  }
                def h(): Object = print()
              }
              new B(): Object
            }
            ()
          }
      }
      ()
    }
} of class class dotty.tools.dotc.ast.Trees$TypeDef # 281
exception while transforming package <empty> {
  final lazy module val test: test$ = new test$()
  @scala.annotation.internal.SourceFile("abc.scala") final module class test$ extends Object {
    def <init>(): Unit =
      {
        super()
        ()
      }
    def f(x: Object): Unit =
      {
        def print(): Object = x
        class A extends Object {
          def <init>(): Unit =
            {
              super()
              {
                class B extends Object {
                  def <init>(): Unit =
                    {
                      super()
                      ()
                    }
                  def h(): Object = print()
                }
                new B(): Object
              }
              ()
            }
        }
        ()
      }
  }
} of class class dotty.tools.dotc.ast.Trees$PackageDef # 282

exception occurred while compiling abc.scala
Exception in thread "main" java.lang.AssertionError: assertion failed: failure to construct path from method h/class B/class A/object test/package <empty>/package <root> to `this` of class A in object test;
class B in class A does not have an outer accessor
        at scala.Predef$.assert(Predef.scala:165)
        at dotty.tools.dotc.transform.ExplicitOuter$OuterOps$.loop$1(ExplicitOuter.scala:337)
        at dotty.tools.dotc.transform.ExplicitOuter$OuterOps$.path$extension(ExplicitOuter.scala:343)
        at dotty.tools.dotc.transform.LambdaLift$LambdaLifter.memberRef(LambdaLift.scala:446)
        at dotty.tools.dotc.transform.LambdaLift$LambdaLifter.dotty$tools$dotc$transform$LambdaLift$LambdaLifter$$proxyRef(LambdaLift.scala:452)
        at dotty.tools.dotc.transform.LambdaLift$LambdaLifter$$anonfun$addFreeArgs$1.apply(LambdaLift.scala:457)
        at dotty.tools.dotc.transform.LambdaLift$LambdaLifter$$anonfun$addFreeArgs$1.apply(LambdaLift.scala:457)
        at scala.collection.immutable.List.map(List.scala:273)
        at dotty.tools.dotc.transform.LambdaLift$LambdaLifter.addFreeArgs(LambdaLift.scala:457)
        at dotty.tools.dotc.transform.LambdaLift$LambdaLifter.transformApply(LambdaLift.scala:518)
        at dotty.tools.dotc.transform.LambdaLift$LambdaLifter.transformApply(LambdaLift.scala:77)
<snipped>