anonymous-class example from the website - hit x. in REPL - crash:

scala> val x = new AnyRef { def kltpzyxm = "back to the 5th dimension" }
x: java.lang.Object{def kltpzyxm: java.lang.String} = $anon$1@1387498

scala> x.java.lang.AssertionError: assertion failed: fatal: has non-class owner value x after flatten.
at scala.Predef$.assert(Predef.scala:103)
at scala.tools.nsc.symtab.Symbols$Symbol.scala$tools$nsc$symtab$Symbols$$flattenName(Symbols.scala:614)
at scala.tools.nsc.symtab.Symbols$ClassSymbol.name(Symbols.scala:2043)
at scala.tools.nsc.symtab.Symbols$ClassSymbol.name(Symbols.scala:2013)
at scala.reflect.generic.Symbols$AbsSymbol.isRefinementClass(Symbols.scala:145)
at scala.tools.nsc.symtab.Symbols$Symbol.defaultFlagMask(Symbols.scala:1711)
at scala.tools.nsc.symtab.Symbols$Symbol.defaultFlagString(Symbols.scala:1714)
at scala.tools.nsc.symtab.Symbols$Symbol.defString(Symbols.scala:1718)
at scala.tools.nsc.symtab.Scopes$Scope$$anonfun$mkString$1.apply(Scopes.scala:316)
at scala.tools.nsc.symtab.Scopes$Scope$$anonfun$mkString$1.apply(Scopes.scala:316)
at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:194)
at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:194)
at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:59)
at scala.collection.immutable.List.foreach(List.scala:45)
at scala.collection.TraversableLike$class.map(TraversableLike.scala:194)
at scala.collection.immutable.List.map(List.scala:45)
at scala.tools.nsc.symtab.Scopes$Scope.mkString(Scopes.scala:316)
at scala.tools.nsc.symtab.Types$CompoundType.safeToString(Types.scala:1377)
at scala.reflect.generic.Types$AbsType.toString(Types.scala:27)
at java.lang.String.valueOf(String.java:2826)
at scala.runtime.StringAdd.$plus(StringAdd.scala:16)
at scala.tools.nsc.interpreter.JLineCompletion$TypeMemberCompletion.completions(JLineCompletion.scala:118)
at scala.tools.nsc.interpreter.CompletionAware$class.completionsFor(CompletionAware.scala:68)
at scala.tools.nsc.interpreter.JLineCompletion$TypeMemberCompletion.completionsFor(JLineCompletion.scala:99)
at scala.tools.nsc.interpreter.CompletionAware$$anonfun$2.apply(CompletionAware.scala:76)
at scala.tools.nsc.interpreter.CompletionAware$$anonfun$2.apply(CompletionAware.scala:76)
at scala.Option.map(Option.scala:134)
at scala.tools.nsc.interpreter.CompletionAware$class.completionsFor(CompletionAware.scala:76)
at scala.tools.nsc.interpreter.JLineCompletion$ids$.completionsFor(JLineCompletion.scala:155)
at scala.tools.nsc.interpreter.JLineCompletion$$anonfun$topLevelFor$1.apply(JLineCompletion.scala:262)
at scala.tools.nsc.interpreter.JLineCompletion$$anonfun$topLevelFor$1.apply(JLineCompletion.scala:261)
at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:59)
at scala.collection.immutable.List.foreach(List.scala:45)
at scala.tools.nsc.interpreter.JLineCompletion.topLevelFor(JLineCompletion.scala:261)
at scala.tools.nsc.interpreter.JLineCompletion$JLineTabCompletion$$anonfun$regularCompletion$1$1.apply(JLineCompletion.scala:357)
at scala.tools.nsc.interpreter.JLineCompletion$JLineTabCompletion$$anonfun$regularCompletion$1$1.apply(JLineCompletion.scala:357)
at scala.tools.nsc.interpreter.JLineCompletion$JLineTabCompletion.tryCompletion$1(JLineCompletion.scala:332)
at scala.tools.nsc.interpreter.JLineCompletion$JLineTabCompletion.regularCompletion$1(JLineCompletion.scala:357)
at scala.tools.nsc.interpreter.JLineCompletion$JLineTabCompletion$$anonfun$complete$2.apply(JLineCompletion.scala:368)
at scala.tools.nsc.interpreter.JLineCompletion$JLineTabCompletion$$anonfun$complete$2.apply(JLineCompletion.scala:368)
at scala.Option.orElse(Option.scala:219)
at scala.tools.nsc.interpreter.JLineCompletion$JLineTabCompletion.complete(JLineCompletion.scala:368)
at scala.tools.nsc.interpreter.JLineReader$$anon$1.complete(JLineReader.scala:31)
at scala.tools.jline.console.completer.ArgumentCompleter.complete(ArgumentCompleter.java:150)
at scala.tools.jline.console.ConsoleReader.complete(ConsoleReader.java:1518)
at scala.tools.jline.console.ConsoleReader.readLine(ConsoleReader.java:1291)
at scala.tools.jline.console.ConsoleReader.readLine(ConsoleReader.java:1149)
at scala.tools.nsc.interpreter.JLineReader.readOneLine(JLineReader.scala:70)
at scala.tools.nsc.interpreter.InteractiveReader$$anonfun$readLine$2.apply(InteractiveReader.scala:43)
at scala.tools.nsc.interpreter.InteractiveReader$$anonfun$readLine$2.apply(InteractiveReader.scala:43)
at scala.tools.nsc.interpreter.InteractiveReader$.restartSysCalls(InteractiveReader.scala:50)
at scala.tools.nsc.interpreter.InteractiveReader$class.readLine(InteractiveReader.scala:43)
at scala.tools.nsc.interpreter.JLineReader.readLine(JLineReader.scala:17)
at scala.tools.nsc.interpreter.ILoop.readOneLine$1(ILoop.scala:548)
at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:560)
at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:827)
at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:67)
at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:80)
at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:89)
at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)

The repl compiler has crashed spectacularly.