scala> case class verywrong(`a b`: Int, a: String)
error: 
     while compiling: <console>
        during phase: constructors
     library version: version 2.10.4
    compiler version: version 2.10.4
  reconstructed args: 

  last tree to typer: Ident(a b)
              symbol: value a b (flags: <param> <triedcooking>)
   symbol definition: a b: Int
       symbol owners: value a b -> constructor verywrong -> class verywrong -> object $iw -> object $iw -> object $read -> package $line5
      context owners: class verywrong -> object $iw -> object $iw -> object $read -> package $line5

== Enclosing template or block ==

Template( // val <local verywrong>: <notype> in class verywrong, tree.tpe=verywrong
  "java.lang.Object", "scala.Product", "scala.Serializable" // parents
  ValDef(
    private
    "_"
    <tpt>
    <empty>
  )
  // 16 statements
  ValDef( // private[this] val a b: Int in class verywrong
    private <local> <caseaccessor> <paramaccessor> <triedcooking>
    "a$u0020b "
    <tpt> // tree.tpe=Int
    <empty>
  )
  DefDef( // val a b(): Int in class verywrong
    <method> <stable> <caseaccessor> <accessor> <paramaccessor> <triedcooking>
    "a$u0020b"
    []
    List(Nil)
    <tpt> // tree.tpe=Int
    verywrong.this."a$u0020b " // private[this] val a b: Int in class verywrong, tree.tpe=Int
  )
  ValDef( // private[this] val a: String in class verywrong
    private <local> <caseaccessor> <paramaccessor> <triedcooking>
    "a "
    <tpt> // tree.tpe=String
    <empty>
  )
  DefDef( // val a(): String in class verywrong
    <method> <stable> <caseaccessor> <accessor> <paramaccessor> <triedcooking>
    "a"
    []
    List(Nil)
    <tpt> // tree.tpe=String
    verywrong.this."a " // private[this] val a: String in class verywrong, tree.tpe=String
  )
  DefDef( // def <init>(a b: Int,a: String): verywrong in class verywrong
    <method> <triedcooking>
    "<init>"
    []
    // 1 parameter list
    ValDef( // a b: Int
      <param> <paramaccessor> <triedcooking>
      "a$u0020b"
      <tpt> // tree.tpe=Int
      <empty>
    )
    ValDef( // a: String
      <param> <paramaccessor>
      "a"
      <tpt> // tree.tpe=String
      <empty>
    )
    <tpt> // tree.tpe=verywrong
    Block( // tree.tpe=Unit
      // 2 statements
      Apply( // def <init>(): Object in class Object, tree.tpe=Object
        verywrong.super."<init>" // def <init>(): Object in class Object, tree.tpe=()Object
        Nil
      )
      Apply( // def $init$(): Unit in class Product$class, tree.tpe=Unit
        verywrong.this.$asInstanceOf[Product$class]()."$init$" // def $init$(): Unit in class Product$class, tree.tpe=()Unit
        Nil
      )
      ()
    )
  )
  DefDef( // def copy(a b: Int,a: String): verywrong in class verywrong
    <method> <synthetic>
    "copy"
    []
    // 1 parameter list
    ValDef( // a b: Int
      <param> <defaultparam/trait> <triedcooking>
      "a$u0020b"
      <tpt> // tree.tpe=Int
      <empty>
    )
    ValDef( // a: String
      <param> <defaultparam/trait> <triedcooking>
      "a"
      <tpt> // tree.tpe=String
      <empty>
    )
    <tpt> // tree.tpe=verywrong
    Apply( // def <init>(a b: Int,a: String): verywrong in class verywrong, tree.tpe=verywrong
      new verywrong."<init>" // def <init>(a b: Int,a: String): verywrong in class verywrong, tree.tpe=(a b: Int, a: String)verywrong
      // 2 arguments
      "a$u0020b" // a b: Int, tree.tpe=Int
      "a" // a: String, tree.tpe=String
    )
  )
  DefDef( // def copy$default$1(): Int in class verywrong
    <method> <synthetic> <defaultparam/trait>
    "copy$default$1"
    []
    List(Nil)
    <tpt> // tree.tpe=Int
    Apply( // val a b(): Int in class verywrong, tree.tpe=Int
      verywrong.this."a$u0020b" // val a b(): Int in class verywrong, tree.tpe=()Int
      Nil
    )
  )
  DefDef( // def copy$default$2(): String in class verywrong
    <method> <synthetic> <defaultparam/trait>
    "copy$default$2"
    []
    List(Nil)
    <tpt> // tree.tpe=String
    Apply( // val a(): String in class verywrong, tree.tpe=String
      verywrong.this."a" // val a(): String in class verywrong, tree.tpe=()String
      Nil
    )
  )
  DefDef( // override def productPrefix(): String in class verywrong
    <method> override <synthetic>
    "productPrefix"
    []
    List(Nil)
    <tpt> // tree.tpe=String
    "verywrong"
  )
  DefDef( // def productArity(): Int in class verywrong
    <method> <synthetic>
    "productArity"
    []
    List(Nil)
    <tpt> // tree.tpe=Int
    2
  )
  DefDef( // def productElement(x$1: Int): Object in class verywrong
    <method> <synthetic>
    "productElement"
    []
    // 1 parameter list
    ValDef( // x$1: Int
      <param> <synthetic> <triedcooking>
      "x$1"
      <tpt> // tree.tpe=Int
      <empty>
    )
    <tpt> // tree.tpe=Object
    Block( // tree.tpe=Object
      ValDef( // case val x1: Int
        case <synthetic> <triedcooking>
        "x1"
        <tpt> // tree.tpe=Int
        "x$1" // x$1: Int, tree.tpe=Int
      )
      Match( // tree.tpe=Object
        Typed( // tree.tpe=Int
          "x1" // case val x1: Int, tree.tpe=Int
          <tpt> // tree.tpe=Int
        )
        // 3 cases
        CaseDef( // tree.tpe=Object
          0
          Apply( // def box(x: Int): Integer in object Int, tree.tpe=Object
            "scala"."Int"."box" // def box(x: Int): Integer in object Int, tree.tpe=(x: Int)Integer
            Apply( // val a b(): Int in class verywrong, tree.tpe=Int
              verywrong.this."a$u0020b" // val a b(): Int in class verywrong, tree.tpe=()Int
              Nil
            )
          )
        )
        CaseDef( // tree.tpe=String
          1
          Apply( // val a(): String in class verywrong, tree.tpe=String
            verywrong.this."a" // val a(): String in class verywrong, tree.tpe=()String
            Nil
          )
        )
        CaseDef( // tree.tpe=Nothing
          "_" // tree.tpe=Int
          Throw( // tree.tpe=Nothing
            Apply( // def <init>(x$1: String): IndexOutOfBoundsException in class IndexOutOfBoundsException, tree.tpe=IndexOutOfBoundsException
              new IndexOutOfBoundsException."<init>" // def <init>(x$1: String): IndexOutOfBoundsException in class IndexOutOfBoundsException, tree.tpe=(x$1: String)IndexOutOfBoundsException
              Apply( // def toString(): String in class Object, tree.tpe=String
                scala.Int.box(x$1)."toString" // def toString(): String in class Object, tree.tpe=()String
                Nil
              )
            )
          )
        )
      )
    )
  )
  DefDef( // override def productIterator(): Iterator in class verywrong
    <method> override <synthetic>
    "productIterator"
    []
    List(Nil)
    <tpt> // tree.tpe=Iterator
    Apply( // def typedProductIterator(x: Product): Iterator in object ScalaRunTime, tree.tpe=Iterator
      runtime.this."ScalaRunTime"."typedProductIterator" // def typedProductIterator(x: Product): Iterator in object ScalaRunTime, tree.tpe=(x: Product)Iterator
      This("verywrong")case class verywrong extends Product with Serializable, tree.tpe=verywrong
    )
  )
  DefDef( // def canEqual(x$1: Object): Boolean in class verywrong
    <method> <synthetic> <triedcooking>
    "canEqual"
    []
    // 1 parameter list
    ValDef( // x$1: Object
      <param> <synthetic> <triedcooking>
      "x$1"
      <tpt> // tree.tpe=Object
      <empty>
    )
    <tpt> // tree.tpe=Boolean
    Apply( // final def $isInstanceOf[T0 >: ? <: ?](): Boolean in class Object, tree.tpe=Boolean
      TypeApply( // final def $isInstanceOf[T0 >: ? <: ?](): Boolean in class Object, tree.tpe=()Boolean
        "x$1"."$isInstanceOf" // final def $isInstanceOf[T0 >: ? <: ?](): Boolean in class Object, tree.tpe=[T0 >: ? <: ?]()Boolean
        <tpt> // tree.tpe=verywrong
      )
      Nil
    )
  )
  DefDef( // override def hashCode(): Int in class verywrong
    <method> override <synthetic>
    "hashCode"
    []
    List(Nil)
    <tpt> // tree.tpe=Int
    Block( // tree.tpe=Int
      // 3 statements
      ValDef( // var acc: Int
        <mutable> <synthetic> <triedcooking>
        "acc"
        <tpt> // tree.tpe=Int
        -889275714
      )
      Assign( // tree.tpe=Unit
        "acc" // var acc: Int, tree.tpe=Int
        Apply( // def mix(x$1: Int,x$2: Int): Int in object Statics, tree.tpe=Int
          Statics.this."mix" // def mix(x$1: Int,x$2: Int): Int in object Statics, tree.tpe=(x$1: Int, x$2: Int)Int
          // 2 arguments
          "acc" // var acc: Int, tree.tpe=Int
          Apply( // val a b(): Int in class verywrong, tree.tpe=Int
            verywrong.this."a$u0020b" // val a b(): Int in class verywrong, tree.tpe=()Int
            Nil
          )
        )
      )
      Assign( // tree.tpe=Unit
        "acc" // var acc: Int, tree.tpe=Int
        Apply( // def mix(x$1: Int,x$2: Int): Int in object Statics, tree.tpe=Int
          Statics.this."mix" // def mix(x$1: Int,x$2: Int): Int in object Statics, tree.tpe=(x$1: Int, x$2: Int)Int
          // 2 arguments
          "acc" // var acc: Int, tree.tpe=Int
          Apply( // def anyHash(x$1: Object): Int in object Statics, tree.tpe=Int
            Statics.this."anyHash" // def anyHash(x$1: Object): Int in object Statics, tree.tpe=(x$1: Object)Int
            Apply( // val a(): String in class verywrong, tree.tpe=String
              verywrong.this."a" // val a(): String in class verywrong, tree.tpe=()String
              Nil
            )
          )
        )
      )
      Apply( // def finalizeHash(x$1: Int,x$2: Int): Int in object Statics, tree.tpe=Int
        Statics.this."finalizeHash" // def finalizeHash(x$1: Int,x$2: Int): Int in object Statics, tree.tpe=(x$1: Int, x$2: Int)Int
        // 2 arguments
        "acc" // var acc: Int, tree.tpe=Int
        2
      )
    )
  )
  DefDef( // override def toString(): String in class verywrong
    <method> override <synthetic>
    "toString"
    []
    List(Nil)
    <tpt> // tree.tpe=String
    Apply( // def _toString(x: Product): String in object ScalaRunTime, tree.tpe=String
      ScalaRunTime.this."_toString" // def _toString(x: Product): String in object ScalaRunTime, tree.tpe=(x: Product)String
      This("verywrong")case class verywrong extends Product with Serializable, tree.tpe=verywrong
    )
  )
  DefDef( // override def equals(x$1: Object): Boolean in class verywrong
    <method> override <synthetic>
    "equals"
    []
    // 1 parameter list
    ValDef( // x$1: Object
      <param> <synthetic> <triedcooking>
      "x$1"
      <tpt> // tree.tpe=Object
      <empty>
    )
    <tpt> // tree.tpe=Boolean
    Apply( // def ||(x: Boolean): Boolean in class Boolean, tree.tpe=Boolean
      verywrong.this.eq(x$1)."$bar$bar" // def ||(x: Boolean): Boolean in class Boolean, tree.tpe=(x: Boolean)Boolean
      Apply( // def &&(x: Boolean): Boolean in class Boolean, tree.tpe=Boolean
        {
  case <synthetic> val x1: Object = x$1;
  case5(){
    if (x1.$isInstanceOf[verywrong]())
      matchEnd4(true)
    else
      case6()
  };
  case6(){
    matchEnd4(false)
  };
  matchEnd4(x: Boolean){
    x
  }
}."$amp$amp" // def &&(x: Boolean): Boolean in class Boolean, tree.tpe=(x: Boolean)Boolean
        Block( // tree.tpe=Boolean
          ValDef( // val verywrong$1: verywrong
            <synthetic> <triedcooking>
            "verywrong$1"
            <tpt> // tree.tpe=verywrong
            Apply( // final def $asInstanceOf[T0 >: ? <: ?](): T0 in class Object, tree.tpe=verywrong
              TypeApply( // final def $asInstanceOf[T0 >: ? <: ?](): T0 in class Object, tree.tpe=()verywrong
                "x$1"."$asInstanceOf" // final def $asInstanceOf[T0 >: ? <: ?](): T0 in class Object, tree.tpe=[T0 >: ? <: ?]()T0
                <tpt> // tree.tpe=verywrong
              )
              Nil
            )
          )
          Apply( // def &&(x: Boolean): Boolean in class Boolean, tree.tpe=Boolean
            verywrong.this.a b().==(verywrong$1.a b()).&&(verywrong.this.a().==(verywrong$1.a()))."$amp$amp" // def &&(x: Boolean): Boolean in class Boolean, tree.tpe=(x: Boolean)Boolean
            Apply( // def canEqual(x$1: Object): Boolean in class verywrong, tree.tpe=Boolean
              "verywrong$1"."canEqual" // def canEqual(x$1: Object): Boolean in class verywrong, tree.tpe=(x$1: Object)Boolean
              This("verywrong")case class verywrong extends Product with Serializable, tree.tpe=verywrong
            )
          )
        )
      )
    )
  )
)

uncaught exception during compilation: scala.reflect.internal.Types$TypeError
scala.reflect.internal.Types$TypeError: type mismatch;
 found   : Int
 required: String
	at scala.tools.nsc.typechecker.Contexts$Context.issue(Contexts.scala:401)
	at scala.tools.nsc.typechecker.ContextErrors$ErrorUtils$.issueTypeError(ContextErrors.scala:103)
	at scala.tools.nsc.typechecker.ContextErrors$ErrorUtils$.issueNormalTypeError(ContextErrors.scala:87)
	at scala.tools.nsc.typechecker.ContextErrors$TyperContextErrors$TyperErrorGen$.AdaptTypeError(ContextErrors.scala:195)
	at scala.tools.nsc.typechecker.Typers$Typer.fallBack$1(Typers.scala:1278)
	at scala.tools.nsc.typechecker.Typers$Typer.adapt(Typers.scala:1283)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5660)
	at scala.tools.nsc.interpreter.ReplGlobal$$anon$1$$anon$2.typed(ReplGlobal.scala:29)
	at scala.tools.nsc.typechecker.Typers$Typer.typedAssign$1(Typers.scala:4294)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:5578)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5642)
	at scala.tools.nsc.interpreter.ReplGlobal$$anon$1$$anon$2.typed(ReplGlobal.scala:29)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:5704)
	at scala.tools.nsc.typechecker.Typers$Typer.typedPos(Typers.scala:5709)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.scala$tools$nsc$transform$Constructors$ConstructorTransformer$$mkAssign$1(Constructors.scala:121)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.scala$tools$nsc$transform$Constructors$ConstructorTransformer$$copyParam$1(Constructors.scala:128)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer$$anonfun$8.apply(Constructors.scala:268)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer$$anonfun$8.apply(Constructors.scala:259)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
	at scala.collection.immutable.List.foreach(List.scala:318)
	at scala.collection.TraversableLike$class.map(TraversableLike.scala:244)
	at scala.collection.AbstractTraversable.map(Traversable.scala:105)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.transformClassTemplate(Constructors.scala:259)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer$$anonfun$transform$1.apply(Constructors.scala:575)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer$$anonfun$transform$1.apply(Constructors.scala:575)
	at scala.reflect.internal.Trees$class.deriveClassDef(Trees.scala:1616)
	at scala.reflect.internal.SymbolTable.deriveClassDef(SymbolTable.scala:13)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.transform(Constructors.scala:575)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.transformClassTemplate(Constructors.scala:170)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer$$anonfun$transform$1.apply(Constructors.scala:575)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer$$anonfun$transform$1.apply(Constructors.scala:575)
	at scala.reflect.internal.Trees$class.deriveClassDef(Trees.scala:1616)
	at scala.reflect.internal.SymbolTable.deriveClassDef(SymbolTable.scala:13)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.transform(Constructors.scala:575)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.transformClassTemplate(Constructors.scala:170)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer$$anonfun$transform$1.apply(Constructors.scala:575)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer$$anonfun$transform$1.apply(Constructors.scala:575)
	at scala.reflect.internal.Trees$class.deriveClassDef(Trees.scala:1616)
	at scala.reflect.internal.SymbolTable.deriveClassDef(SymbolTable.scala:13)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.transform(Constructors.scala:575)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.transformClassTemplate(Constructors.scala:170)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer$$anonfun$transform$1.apply(Constructors.scala:575)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer$$anonfun$transform$1.apply(Constructors.scala:575)
	at scala.reflect.internal.Trees$class.deriveClassDef(Trees.scala:1616)
	at scala.reflect.internal.SymbolTable.deriveClassDef(SymbolTable.scala:13)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.transform(Constructors.scala:575)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.transform(Constructors.scala:30)
	at scala.reflect.api.Trees$Transformer$$anonfun$transformStats$1.apply(Trees.scala:2927)
	at scala.reflect.api.Trees$Transformer$$anonfun$transformStats$1.apply(Trees.scala:2925)
	at scala.collection.immutable.List.loop$1(List.scala:170)
	at scala.collection.immutable.List.mapConserve(List.scala:186)
	at scala.reflect.api.Trees$Transformer.transformStats(Trees.scala:2925)
	at scala.reflect.internal.Trees$$anonfun$itransform$7.apply(Trees.scala:1298)
	at scala.reflect.internal.Trees$$anonfun$itransform$7.apply(Trees.scala:1298)
	at scala.reflect.api.Trees$Transformer.atOwner(Trees.scala:2936)
	at scala.reflect.internal.Trees$class.itransform(Trees.scala:1297)
	at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:13)
	at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:13)
	at scala.reflect.api.Trees$Transformer.transform(Trees.scala:2897)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.transform(Constructors.scala:577)
	at scala.tools.nsc.transform.Constructors$ConstructorTransformer.transform(Constructors.scala:30)
	at scala.tools.nsc.ast.Trees$Transformer.transformUnit(Trees.scala:227)
	at scala.tools.nsc.transform.Transform$Phase.apply(Transform.scala:30)
	at scala.tools.nsc.Global$GlobalPhase.applyPhase(Global.scala:464)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$run$1.apply(Global.scala:431)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$run$1.apply(Global.scala:431)
	at scala.collection.Iterator$class.foreach(Iterator.scala:727)
	at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
	at scala.tools.nsc.Global$GlobalPhase.run(Global.scala:431)
	at scala.tools.nsc.Global$Run.compileUnitsInternal(Global.scala:1583)
	at scala.tools.nsc.Global$Run.compileUnits(Global.scala:1557)
	at scala.tools.nsc.Global$Run.compileSources(Global.scala:1553)
	at scala.tools.nsc.interpreter.IMain.compileSourcesKeepingRun(IMain.scala:428)
	at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.compileAndSaveRun(IMain.scala:801)
	at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.compile(IMain.scala:761)
	at scala.tools.nsc.interpreter.IMain$Request.compile$lzycompute(IMain.scala:936)
	at scala.tools.nsc.interpreter.IMain$Request.compile(IMain.scala:931)
	at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:603)
	at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:568)
	at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:760)
	at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:805)
	at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:717)
	at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:581)
	at scala.tools.nsc.interpreter.ILoop.innerLoop$1(ILoop.scala:588)
	at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:591)
	at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILoop.scala:882)
	at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:837)
	at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:837)
	at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135)
	at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:837)
	at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:83)
	at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:96)
	at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:105)
	at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)

That entry seems to have slain the compiler.  Shall I replay
your session? I can re-run each line except the last one.
[y/n]