repl: Handle value classes in class-based

... by making any code snippet that defines (or seems to define) a value
class use the original "object-based" wrappers instead.

Author: dwijnand

src/repl/scala/tools/nsc/interpreter/IMain.scala

@@ -827,6 +827,7 @@ class IMain(initialSettings: Settings, protected val out: JPrintWriter) extends
 
     /** handlers for each tree in this request */
     val handlers: List[MemberHandler] = trees map (memberHandlers chooseHandler _)
+    val definesValueClass = handlers.exists(_.definesValueClass)
 
     def defHandlers = handlers collect { case x: MemberDefHandler => x }
 
@@ -915,7 +916,7 @@ class IMain(initialSettings: Settings, protected val out: JPrintWriter) extends
     }
 
     private[interpreter] lazy val ObjectSourceCode: Wrapper =
-      if (isClassBased) new ClassBasedWrapper else new ObjectBasedWrapper
+      if (isClassBased && !definesValueClass) new ClassBasedWrapper else new ObjectBasedWrapper
 
     private object ResultObjectSourceCode extends IMain.CodeAssembler[MemberHandler] {
       /** We only want to generate this code when the result

src/repl/scala/tools/nsc/interpreter/MemberHandlers.scala

@@ -99,6 +99,7 @@ trait MemberHandlers {
     def path            = intp.originalPath(symbol)
     def symbol          = if (member.symbol eq null) NoSymbol else member.symbol
     def definesImplicit = false
+    def definesValueClass = false
     def definesValue    = false
 
     def definesTerm     = Option.empty[TermName]
@@ -205,6 +206,10 @@ trait MemberHandlers {
     override def definedSymbols = List(symbol, symbol.companionSymbol) filterNot (_ == NoSymbol)
     override def definesType = Some(name.toTypeName)
     override def definesTerm = Some(name.toTermName) filter (_ => mods.isCase)
+    override final def definesValueClass: Boolean = member.impl.parents match {
+      case Ident(tpnme.AnyVal) :: _ => true // approximating with a syntactic check
+      case _                        => false
+    }
 
     override def resultExtractionCode(req: Request) =
       codegenln("defined %s %s".format(keyword, name))

test/files/run/repl-class-based-value-class.check

@@ -0,0 +1,8 @@
+
+scala> class Meter(val value: Int) extends AnyVal
+defined class Meter
+
+scala> val x = new Meter(1)
+x: Meter = Meter@XXXXXXXX
+
+scala> :quit

test/files/run/repl-class-based-value-class.scala

@@ -0,0 +1,15 @@
+import scala.tools.nsc.Settings
+import scala.tools.partest.{ Hashless, ReplTest }
+
+object Test extends ReplTest with Hashless {
+  override def transformSettings(s: Settings) = {
+    s.Yreplclassbased.value  = true
+    s.YreplMagicImport.value = true
+    s
+  }
+
+  def code = """
+    |class Meter(val value: Int) extends AnyVal
+    |val x = new Meter(1)
+    |""".stripMargin
+}