Add documentation

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/Denotations.scala

@@ -1192,6 +1192,13 @@ object Denotations {
     def staticRef(path: Name, generateStubs: Boolean = true, isPackage: Boolean = false)(implicit ctx: Context): Denotation = {
       def select(prefix: Denotation, selector: Name): Denotation = {
         val owner = prefix.disambiguate(_.info.isParameterless)
+        def isPackageFromCoreLibMissing: Boolean = {
+          owner.symbol == defn.RootClass &&
+          {
+            selector == nme.scala_ || // if the scala package is missing, the stdlib must be missing
+            selector == nme.scalaShadowing // if the scalaShadowing package is missing, the dotty library must be missing
+          }
+        }
         if (owner.exists) {
           val result = if (isPackage) owner.info.decl(selector) else owner.info.member(selector)
           if (result.exists) result
@@ -1200,8 +1207,7 @@ object Denotations {
               if (generateStubs) missingHook(owner.symbol.moduleClass, selector)
               else NoSymbol
             if (alt.exists) alt.denot
-            else if (owner.symbol == defn.RootClass && (selector == nme.scala_ || selector == nme.scalaShadowing))
-              throw new MissingCoreLibraryException(selector.toString)
+            else if (isPackageFromCoreLibMissing) throw new MissingCoreLibraryException(selector.toString)
             else MissingRef(owner, selector)
           }
         }

compiler/test/dotty/tools/vulpix/TestConfiguration.scala

@@ -25,7 +25,7 @@ object TestConfiguration {
 
   val classPath = mkClassPath(Jars.dottyTestDeps)
 
-  def mkClassPath(deps: List[String]) = {
+  def mkClassPath(deps: List[String]): Array[String] = {
     val paths = deps map { p =>
       val file = new java.io.File(p)
       assert(