Fix scala#239 - handling of package objects

References to `.package` are now also inserted if the
accessed member comes from a class inherited by a package
object.

Author: odersky

src/dotty/tools/dotc/transform/FirstTransform.scala

@@ -124,7 +124,7 @@ class FirstTransform extends MiniPhaseTransform with IdentityDenotTransformer wi
     normalizeType {
       val qual = tree.qualifier
       qual.symbol.moduleClass.denot match {
-        case pkg: PackageClassDenotation if tree.symbol.maybeOwner.isPackageObject =>
+        case pkg: PackageClassDenotation if !tree.symbol.maybeOwner.is(Package) =>
           cpy.Select(tree)(qual select pkg.packageObj.symbol, tree.name)
         case _ =>
           tree

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

@@ -114,15 +114,15 @@ trait TypeAssigner {
   def ensureAccessible(tpe: Type, superAccess: Boolean, pos: Position)(implicit ctx: Context): Type = {
 
     def tryInsertPackageObj(tpe: NamedType, d: Denotation): Type = {
-      def tryInsert: Type =
-        if (!(d.symbol.maybeOwner is Package)) {
-          val symOwner = d.alternatives.head.symbol.owner
-          if (symOwner.isPackageObject) tpe.derivedSelect(symOwner.thisType)
-          else tpe
-        } else tpe
+      def tryInsert(pkgClass: SymDenotation): Type = pkgClass match {
+        case pkgCls: PackageClassDenotation if !(d.symbol.maybeOwner is Package) =>
+          tpe.derivedSelect(pkgCls.packageObj.valRef)
+        case _ =>
+          tpe
+      }
       tpe.prefix match {
-        case pre: ThisType if pre.cls is Package => tryInsert
-        case pre: TermRef if pre.symbol is Package => tryInsert
+        case pre: ThisType if pre.cls is Package => tryInsert(pre.cls)
+        case pre: TermRef if pre.symbol is Package => tryInsert(pre.symbol.moduleClass)
         case _ => tpe
       }
     }

tests/pos/i239-packageObj.scala

@@ -0,0 +1,11 @@
+package p {
+  class C[A] { def foo: A = ??? }
+
+  object `package` extends C[String]
+}
+
+object test {
+
+  val x: String = p.foo
+
+}