Merge pull request #469 from dotty-staging/stylecheck

Add stylechecking to test suite, fix style errors

Author: odersky

src/dotty/tools/dotc/typer/Checking.scala

@@ -241,16 +241,20 @@ trait Checking {
   def checkLegalPrefix(tp: Type, selector: Name, pos: Position)(implicit ctx: Context): Unit =
     if (!tp.isLegalPrefixFor(selector)) ctx.error(d"$tp is not a valid prefix for '# $selector'", pos)
 
- /**  Check that `tp` is a class type with a stable prefix. Also, if `traitReq` is
-   *  true check that `tp` is a trait.
+  /** Check that `tp` is a class type with a stable prefix. Also:
+   *  If `traitReq` is true, check that `tp` refers to a trait.
+   *  If `concreteReq` is true, check that `tp` refers to a nonAbstract class. 
    *  Stability checking is disabled in phases after RefChecks.
    *  @return  `tp` itself if it is a class or trait ref, ObjectClass.typeRef if not.
    */
-  def checkClassTypeWithStablePrefix(tp: Type, pos: Position, traitReq: Boolean)(implicit ctx: Context): Type =
+  def checkClassTypeWithStablePrefix(tp: Type, pos: Position, traitReq: Boolean = false, concreteReq: Boolean = false)(implicit ctx: Context): Type =
     tp.underlyingClassRef(refinementOK = false) match {
       case tref: TypeRef =>
         if (ctx.phase <= ctx.refchecksPhase) checkStable(tref.prefix, pos)
-        if (traitReq && !(tref.symbol is Trait)) ctx.error(d"$tref is not a trait", pos)
+        if (traitReq && !(tref.symbol is Trait)) 
+          ctx.error(d"$tref is not a trait", pos)
+        if (concreteReq && false && (tref.symbol is AbstractOrTrait)) 
+          ctx.error(d"${tref.symbol} is abstract; cannot be instantiated, owner = ${ctx.owner}", pos)
         tp
       case _ =>
         ctx.error(d"$tp is not a class type", pos)
@@ -329,7 +333,7 @@ trait NoChecking extends Checking {
   override def checkBounds(args: List[tpd.Tree], poly: PolyType)(implicit ctx: Context): Unit = ()
   override def checkStable(tp: Type, pos: Position)(implicit ctx: Context): Unit = ()
   override def checkLegalPrefix(tp: Type, selector: Name, pos: Position)(implicit ctx: Context): Unit = ()
-  override def checkClassTypeWithStablePrefix(tp: Type, pos: Position, traitReq: Boolean)(implicit ctx: Context): Type = tp
+  override def checkClassTypeWithStablePrefix(tp: Type, pos: Position, traitReq: Boolean, concreteReq: Boolean)(implicit ctx: Context): Type = tp
   override def checkImplicitParamsNotSingletons(vparamss: List[List[ValDef]])(implicit ctx: Context): Unit = ()
   override def checkFeasible(tp: Type, pos: Position, where: => String = "")(implicit ctx: Context): Type = tp
   override def checkNoDoubleDefs(cls: Symbol)(implicit ctx: Context): Unit = ()

src/dotty/tools/dotc/typer/Typer.scala

@@ -347,8 +347,8 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
         val clsDef = TypeDef(x, templ).withFlags(Final)
         typed(cpy.Block(tree)(clsDef :: Nil, New(Ident(x), Nil)), pt)
       case _ =>
-          val tpt1 = typedType(tree.tpt)
-          checkClassTypeWithStablePrefix(tpt1.tpe, tpt1.pos, traitReq = false)
+	      val tpt1 = typedType(tree.tpt)
+	      checkClassTypeWithStablePrefix(tpt1.tpe, tpt1.pos, concreteReq = !ctx.owner.isClass)
         assignType(cpy.New(tree)(tpt1), tpt1)
         // todo in a later phase: checkInstantiatable(cls, tpt1.pos)
     }