Value classes: eliminated half-boxing

We now apply erasure of value classes everywhere. previously,
erasure was disabled in the value class itself. This led to
irregegularities and bugs. See test run/valueclasses-pavlov.scala
for something that led to a ClassCastException before.

3 files changed, 21 insertions, 14 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/Erasure.scala b/src/compiler/scala/tools/nsc/transform/Erasure.scala
index 9381d6432e..072d823c60 100644
--- a/src/compiler/scala/tools/nsc/transform/Erasure.scala
+++ b/src/compiler/scala/tools/nsc/transform/Erasure.scala
@@ -429,6 +429,14 @@ abstract class Erasure extends AddInterfaces
              |both have erased type ${afterPostErasure(bridge.tpe)}""".stripMargin)
       }
       for (bc <- root.baseClasses) {
+        if (settings.debug.value)
+          afterPostErasure(println(
+            s"""check bridge overrides in $bc
+            ${bc.info.nonPrivateDecl(bridge.name)}
+            ${site.memberType(bridge)}
+            ${site.memberType(bc.info.nonPrivateDecl(bridge.name) orElse IntClass)}
+            ${(bridge.matchingSymbol(bc, site))}""".stripMargin))
+
         def overriddenBy(sym: Symbol) =
           sym.matchingSymbol(bc, site).alternatives filter (sym => !sym.isBridge)
         for (overBridge <- afterPostErasure(overriddenBy(bridge))) {
@@ -1046,7 +1054,7 @@ abstract class Erasure extends AddInterfaces
           preEraseIsInstanceOf
         } else if (fn.symbol.owner.isRefinementClass && !fn.symbol.isOverridingSymbol) {
           ApplyDynamic(qualifier, args) setSymbol fn.symbol setPos tree.pos
-        } else if (fn.symbol.isMethodWithExtension) {
+        } else if (fn.symbol.isMethodWithExtension && !fn.symbol.tpe.isErroneous) {
           Apply(gen.mkAttributedRef(extensionMethods.extensionMethod(fn.symbol)), qualifier :: args)
         } else {
           tree
diff --git a/src/compiler/scala/tools/nsc/transform/ExtensionMethods.scala b/src/compiler/scala/tools/nsc/transform/ExtensionMethods.scala
index 0820d3e714..c72fd3681f 100644
--- a/src/compiler/scala/tools/nsc/transform/ExtensionMethods.scala
+++ b/src/compiler/scala/tools/nsc/transform/ExtensionMethods.scala
@@ -70,7 +70,8 @@ abstract class ExtensionMethods extends Transform with TypingTransformers {
     val companionInfo = imeth.owner.companionModule.info
     val candidates = extensionNames(imeth) map (companionInfo.decl(_))
     val matching = candidates filter (alt => normalize(alt.tpe, imeth.owner) matches imeth.tpe)
-    assert(matching.nonEmpty, "no extension method found for "+imeth+" among "+candidates+"/"+extensionNames(imeth))
+    assert(matching.nonEmpty,
+      s"no extension method found for $imeth:${imeth.tpe}+among ${candidates map (c => c.name+":"+c.tpe)} / ${extensionNames(imeth)}")
     matching.head
   }
 
diff --git a/src/reflect/scala/reflect/internal/transform/Erasure.scala b/src/reflect/scala/reflect/internal/transform/Erasure.scala
index cc5b5bb406..977398909f 100644
--- a/src/reflect/scala/reflect/internal/transform/Erasure.scala
+++ b/src/reflect/scala/reflect/internal/transform/Erasure.scala
@@ -203,28 +203,26 @@ trait Erasure {
   def specialErasure(sym: Symbol)(tp: Type): Type =
     if (sym != NoSymbol && sym.enclClass.isJavaDefined)
       erasure(sym)(tp)
-    else if (sym.isTerm && sym.owner.isDerivedValueClass)
-      specialErasureAvoiding(sym.owner, tp)
-    else if (sym.isValue && sym.owner.isMethodWithExtension)
-      specialErasureAvoiding(sym.owner.owner, tp)
+    else if (sym.isClassConstructor)
+      specialConstructorErasure(sym.owner, tp)
     else
       specialScalaErasure(tp)
 
-  def specialErasureAvoiding(clazz: Symbol, tpe: Type): Type = {
+  def specialConstructorErasure(clazz: Symbol, tpe: Type): Type = {
     tpe match {
       case PolyType(tparams, restpe) =>
-        specialErasureAvoiding(clazz, restpe)
+        specialConstructorErasure(clazz, restpe)
       case ExistentialType(tparams, restpe) =>
-        specialErasureAvoiding(clazz, restpe)
+        specialConstructorErasure(clazz, restpe)
       case mt @ MethodType(params, restpe) =>
         MethodType(
-          cloneSymbolsAndModify(params, specialErasureAvoiding(clazz, _)),
-          if (restpe.typeSymbol == UnitClass) erasedTypeRef(UnitClass)
-          else specialErasureAvoiding(clazz, (mt.resultType(mt.paramTypes))))
+          cloneSymbolsAndModify(params, specialScalaErasure),
+          specialConstructorErasure(clazz, restpe))
       case TypeRef(pre, `clazz`, args) =>
         typeRef(pre, clazz, List())
-      case _ =>
-        specialScalaErasure(tpe)
+      case tp =>
+        assert(clazz == ArrayClass || tp.isError, s"unexpected constructor erasure $tp for $clazz")
+        specialScalaErasure(tp)
     }
   }