Have no real intuition why this particular code combination crashes the resident compiler, I just worked my way \
backwards. 

tsf-wpa-2-067:~/workspace/test18/src mcdirmid$ ../../scala/build/quick/bin/scalac -d ../bin/ -resident

nsc> test/ParserXXX.scala

nsc> test/BracesXXX.scala
exception when typing abstract trait Matchable$class extends java.lang.Object with test.ParserXXX#IsLinked$class\
 with scala.ScalaObject$class with test.BracesXXX#Matchable {
  def /*Matchable$class*/$init$(): scala.Unit = {
    ()
  };
  def foo(): test.ParserXXX#NodeImpl = null
}
exception when typing abstract trait BracesXXX extends java.lang.Object with test.ParserXXX with scala.ScalaObje\
ct {
  abstract trait Matchable extends java.lang.Object with test.ParserXXX#IsLinked with scala.ScalaObject {
    def foo(): test.ParserXXX#NodeImpl;
     def test$BracesXXX$Matchable$$$outer(): test.BracesXXX
  };
  abstract trait Matchable$class extends java.lang.Object with test.ParserXXX#IsLinked$class with scala.ScalaObj\
ect$class with test.BracesXXX#Matchable {
    def /*Matchable$class*/$init$(): scala.Unit = {
      ()
    };
    def foo(): test.ParserXXX#NodeImpl = null
  }
}
exception when typing package test {
  abstract trait BracesXXX extends java.lang.Object with test.ParserXXX with scala.ScalaObject {
    abstract trait Matchable extends java.lang.Object with test.ParserXXX#IsLinked with scala.ScalaObject {
      def foo(): test.ParserXXX#NodeImpl;
       def test$BracesXXX$Matchable$$$outer(): test.BracesXXX
    };
    abstract trait Matchable$class extends java.lang.Object with test.ParserXXX#IsLinked$class with scala.ScalaO\
bject$class with test.BracesXXX#Matchable {
      def /*Matchable$class*/$init$(): scala.Unit = {
        ()
      };
      def foo(): test.ParserXXX#NodeImpl = null
    }
  };
  abstract trait BracesXXX$class extends java.lang.Object with test.ParserXXX$class with scala.ScalaObject$class\
 with test.BracesXXX {
    def /*BracesXXX$class*/$init$(): scala.Unit = {
      ()
    }
  }
}
Exception in thread "main" java.lang.AssertionError: assertion failed: ParserXXX.this.type.trait Link$class does\
 no longer exist, phase = erasure
	at scala.Predef$.assert(Predef.scala:95)
	at scala.tools.nsc.symtab.Types$adaptToNewRunMap$.adaptToNewRun(Types.scala:1522)
	at scala.tools.nsc.symtab.Types$adaptToNewRunMap$.apply(Types.scala:1555)
	at scala.tools.nsc.symtab.Types$adaptToNewRunMap$.apply(Types.scala:1511)
	at scala.List$.loop$0(List.scala:239)
	at scala.List$.mapConserve(List.scala:256)
	at scala.tools.nsc.symtab.Types$adaptToNewRunMap$.apply(Types.scala:1564)
	at scala.tools.nsc.symtab.Types$Type.complete(Types.scala:358)
	at scala.tools.nsc.symtab.Symbols$Symbol.info(Symbols.scala:385)
	at scala.tools.nsc.transform.AddInterfaces.scala$tools$nsc$transform$AddInterfaces$$isInterfaceMember(AddInterf\
aces.scala:45)
	at scala.tools.nsc.transform.AddInterfaces$LazyImplClassType$$anonfun$2.apply(AddInterfaces.scala:109)
	at scala.tools.nsc.transform.AddInterfaces$LazyImplClassType$$anonfun$2.apply(AddInterfaces.scala:108)
	at scala.Iterator$class.foreach(Iterator.scala:316)
	at scala.List$$anon$0.foreach(List.scala:471)
	at scala.tools.nsc.transform.AddInterfaces$LazyImplClassType.implDecls(AddInterfaces.scala:108)
	at scala.tools.nsc.transform.AddInterfaces$LazyImplClassType.implType$0(AddInterfaces.scala:133)
	at scala.tools.nsc.transform.AddInterfaces$LazyImplClassType$$anonfun$4.apply(AddInterfaces.scala:138)
	at scala.tools.nsc.transform.AddInterfaces$LazyImplClassType$$anonfun$4.apply(AddInterfaces.scala:138)
	at scala.tools.nsc.symtab.SymbolTable.atPhase(SymbolTable.scala:71)
	at scala.tools.nsc.transform.AddInterfaces$LazyImplClassType.complete(AddInterfaces.scala:138)
	at scala.tools.nsc.symtab.Symbols$Symbol.info(Symbols.scala:385)
	at scala.tools.nsc.symtab.Types$TypeRef.closure(Types.scala:894)
	at scala.tools.nsc.symtab.Types$CompoundType$$anonfun$3.apply(Types.scala:654)
	at scala.tools.nsc.symtab.Types$CompoundType$$anonfun$3.apply(Types.scala:653)
	at scala.List.foreach(List.scala:688)
	at scala.tools.nsc.symtab.Types$CompoundType.computeClosure$0(Types.scala:653)
	at scala.tools.nsc.symtab.Types$CompoundType.closure(Types.scala:712)
	at scala.tools.nsc.symtab.Types$TypeRef.closure(Types.scala:894)
	at scala.tools.nsc.symtab.Types$CompoundType$$anonfun$3.apply(Types.scala:654)
	at scala.tools.nsc.symtab.Types$CompoundType$$anonfun$3.apply(Types.scala:653)
	at scala.List.foreach(List.scala:688)
	at scala.tools.nsc.symtab.Types$CompoundType.computeClosure$0(Types.scala:653)
	at scala.tools.nsc.symtab.Types$CompoundType.closure(Types.scala:712)
	at scala.tools.nsc.symtab.Types$Type.closurePos(Types.scala:312)
	at scala.tools.nsc.symtab.Types$CompoundType.baseType(Types.scala:762)
	at scala.tools.nsc.symtab.Types$TypeRef.baseType(Types.scala:883)
	at scala.tools.nsc.symtab.Types$class.isSubType0(Types.scala:1733)
	at scala.tools.nsc.symtab.SymbolTable.isSubType0(SymbolTable.scala:10)
	at scala.tools.nsc.symtab.Types$class.isSubType(Types.scala:1687)
	at scala.tools.nsc.symtab.SymbolTable.isSubType(SymbolTable.scala:10)
	at scala.tools.nsc.symtab.Types$Type.$less$colon$less(Types.scala:257)
	at scala.tools.nsc.typechecker.Typers$Typer.validateParentClass$0(Typers.scala:618)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$16.apply(Typers.scala:633)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$16.apply(Typers.scala:633)
	at scala.List.foreach(List.scala:688)
	at scala.tools.nsc.typechecker.Typers$Typer.validateParentClasses(Typers.scala:633)
	at scala.tools.nsc.typechecker.Typers$Typer.typedTemplate(Typers.scala:705)
	at scala.tools.nsc.typechecker.Typers$Typer.typedClassDef(Typers.scala:643)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:1472)
	at scala.tools.nsc.transform.Erasure$Eraser.typed1(Erasure.scala:367)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:1807)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:1834)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStat$0(Typers.scala:1016)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$47.apply(Typers.scala:1037)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$47.apply(Typers.scala:1037)
	at scala.List$.loop$0(List.scala:239)
	at scala.List$.mapConserve(List.scala:256)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:1037)
	at scala.tools.nsc.typechecker.Typers$Typer.typedTemplate(Typers.scala:708)
	at scala.tools.nsc.typechecker.Typers$Typer.typedClassDef(Typers.scala:643)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:1472)
	at scala.tools.nsc.transform.Erasure$Eraser.typed1(Erasure.scala:367)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:1807)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:1834)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStat$0(Typers.scala:1016)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$47.apply(Typers.scala:1037)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$47.apply(Typers.scala:1037)
	at scala.List$.loop$0(List.scala:239)
	at scala.List$.mapConserve(List.scala:256)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:1037)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:1468)
	at scala.tools.nsc.transform.Erasure$Eraser.typed1(Erasure.scala:367)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:1807)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:1834)
	at scala.tools.nsc.transform.Erasure$ErasureTransformer$$anonfun$22.apply(Erasure.scala:655)
	at scala.tools.nsc.transform.Erasure$ErasureTransformer$$anonfun$22.apply(Erasure.scala:652)
	at scala.tools.nsc.symtab.SymbolTable.atPhase(SymbolTable.scala:71)
	at scala.tools.nsc.transform.Erasure$ErasureTransformer.transform(Erasure.scala:652)
	at scala.tools.nsc.ast.Trees$Transformer.transformUnit(Trees.scala:1068)
	at scala.tools.nsc.transform.Transform$Phase.apply(Transform.scala:26)
	at scala.tools.nsc.Global$GlobalPhase.applyPhase(Global.scala:218)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$1.apply(Global.scala:207)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$1.apply(Global.scala:207)
	at scala.Iterator$class.foreach(Iterator.scala:316)
	at scala.collection.mutable.ListBuffer$$anon$0.foreach(ListBuffer.scala:216)
	at scala.tools.nsc.Global$GlobalPhase.run(Global.scala:207)
	at scala.tools.nsc.Global$Run.compileSources(Global.scala:471)
	at scala.tools.nsc.Global$Run.compile(Global.scala:537)
	at scala.tools.nsc.Main$$anonfun$0.apply(Main.scala:39)
	at scala.tools.nsc.Main$$anonfun$0.apply(Main.scala:36)
	at scala.tools.nsc.EvalLoop$class.loop(EvalLoop.scala:17)
	at scala.tools.nsc.Main$.loop(Main.scala:16)
	at scala.tools.nsc.EvalLoop$class.loop(EvalLoop.scala:18)
	at scala.tools.nsc.Main$.loop(Main.scala:16)
	at scala.tools.nsc.Main$.resident(Main.scala:36)
	at scala.tools.nsc.Main$.process(Main.scala:71)
	at scala.tools.nsc.Main$.main(Main.scala:98)
	at scala.tools.nsc.Main.main(Main.scala)