crash on compilable code: scala.MatchError: Ident...

[helloqirun]

scalac can compile but dotc crashes.

$ cat abc.scala

import scala.reflect.runtime.universe._
import scala.reflect.runtime.{currentMirror => cm}
object Test extends App {
  val mutant = new { val x = 2 }
  val c = cm.classSymbol(mutant.getClass)
  !=(c)
  println(c.fullName)
  c.info.toString.lines
    .filter(_ != "  private var bitmap$init$0: Boolean") foreach println
}

$ dotc abc.scala

exception while transforming Test.!=(Test.c) of class class dotty.tools.dotc.ast.Trees$Apply # 285
exception while transforming () extends Object() with App {
  val mutant: Object =
    {
      final class $anon() extends Object() {
        val x: Int = 2
      }
      new Object{...}(): Object
    }
  val c: scala.reflect.runtime.package.universe.ClassSymbol =
    scala.reflect.runtime.currentMirror.classSymbol(Test.mutant.getClass())
  Test.!=(Test.c)
  println(Test.c.fullName)
  augmentString(Test.c.info.toString()).lines.filter(
    {
      def $anonfun(_$1: String): Boolean = _$1.!=("  private var bitmap$init$0: Boolean")
      closure($anonfun)
    }
  ).foreach[Unit^](
    {
      def $anonfun(x: Any): Unit^ = println(x)
      closure($anonfun)
    }
  )
} of class class dotty.tools.dotc.ast.Trees$Template # 306
exception while transforming @scala.annotation.internal.SourceFile("abc.scala") final module class Test$() extends Object() with App {
  val mutant: Object =
    {
      final class $anon() extends Object() {
        val x: Int = 2
      }
      new Object{...}(): Object
    }
  val c: scala.reflect.runtime.package.universe.ClassSymbol =
    scala.reflect.runtime.currentMirror.classSymbol(Test.mutant.getClass())
  Test.!=(Test.c)
  println(Test.c.fullName)
  augmentString(Test.c.info.toString()).lines.filter(
    {
      def $anonfun(_$1: String): Boolean = _$1.!=("  private var bitmap$init$0: Boolean")
      closure($anonfun)
    }
  ).foreach[Unit^](
    {
      def $anonfun(x: Any): Unit^ = println(x)
      closure($anonfun)
    }
  )
} of class class dotty.tools.dotc.ast.Trees$TypeDef # 307
exception while transforming package <empty> {
  final lazy module val Test: Test$ = new Test$()
  @scala.annotation.internal.SourceFile("abc.scala") final module class Test$() extends Object() with App {
    val mutant: Object =
      {
        final class $anon() extends Object() {
          val x: Int = 2
        }
        new Object{...}(): Object
      }
    val c: scala.reflect.runtime.package.universe.ClassSymbol =
      scala.reflect.runtime.currentMirror.classSymbol(Test.mutant.getClass())
    Test.!=(Test.c)
    println(Test.c.fullName)
    augmentString(Test.c.info.toString()).lines.filter(
      {
        def $anonfun(_$1: String): Boolean = _$1.!=("  private var bitmap$init$0: Boolean")
        closure($anonfun)
      }
    ).foreach[Unit^](
      {
        def $anonfun(x: Any): Unit^ = println(x)
        closure($anonfun)
      }
    )
  }
} of class class dotty.tools.dotc.ast.Trees$PackageDef # 308

exception occurred while compiling abc.scala
Exception in thread "main" scala.MatchError: Ident($bang$eq) (of class dotty.tools.dotc.ast.Trees$Ident)
        at dotty.tools.dotc.transform.InterceptedMethods.qual$lzycompute$1(InterceptedMethods.scala:99)
        at dotty.tools.dotc.transform.InterceptedMethods.qual$1(InterceptedMethods.scala:99)
        at dotty.tools.dotc.transform.InterceptedMethods.transformApply(InterceptedMethods.scala:106)
        at dotty.tools.dotc.transform.TreeTransforms$TreeTransformer.goApply(TreeTransform.scala:602)
        at dotty.tools.dotc.transform.TreeTransforms$TreeTransformer.transformUnnamed(TreeTransform.scala:1005)
        at dotty.tools.dotc.transform.TreeTransforms$TreeTransformer$$anonfun$transform$2.apply(TreeTransform.scala:1179)
        at dotty.tools.dotc.transform.TreeTransforms$TreeTransformer$$anonfun$transform$2.apply(TreeTransform.scala:1171)
        at dotty.tools.dotc.reporting.Reporting$class.traceIndented(Reporter.scala:132)
        at dotty.tools.dotc.core.Contexts$Context.traceIndented(Contexts.scala:57)
<snipped>