term and type reftrees are now reified uniformly

Top-level (i.e. owned by a package) => Ident(symbol)
Nested (i.e. owned by an object or a package object) => Select(owner, symbol)
Inner (i.e. owned by a static class) => selectTerm/selectType(owner, name)
Non-locatable (i.e. everything else) => see GenTrees.scala for more details

Changes w.r.t the previous approaches:
  * Top-level refs are no longer reified as Select(This(package), symbol).
    Proposed reification scheme is as resistant to resetAttrs as previous one,
    but is at the same time much shorter.
  * Refs to definitions from package objects are no longer Ident(symbol).
    Otherwise reflective compilation of things like `_ :: _` fails.
  * Contents of Predef._ and scala._ are no longer treated specially.
    This increases the size of reificode, but is more hygienic.

1 files changed, 7 insertions, 5 deletions

diff --git a/src/compiler/scala/reflect/reify/codegen/GenTrees.scala b/src/compiler/scala/reflect/reify/codegen/GenTrees.scala
index 7c7a79e774..9894e359b4 100644
--- a/src/compiler/scala/reflect/reify/codegen/GenTrees.scala
+++ b/src/compiler/scala/reflect/reify/codegen/GenTrees.scala
@@ -153,10 +153,12 @@ trait GenTrees {
         else mirrorCall(nme.Ident, reify(name))
 
       case Select(qual, name) =>
-        if (sym == NoSymbol || sym.name == name)
-          reifyProduct(tree)
-        else
-          reifyProduct(Select(qual, sym.name))
+        if (qual.symbol != null && qual.symbol.isPackage) {
+          mirrorBuildCall(nme.Ident, reify(sym))
+        } else {
+          val effectiveName = if (sym != null && sym != NoSymbol) sym.name else name
+          reifyProduct(Select(qual, effectiveName))
+        }
 
       case _ =>
         throw new Error("internal error: %s (%s, %s) is not supported".format(tree, tree.productPrefix, tree.getClass))
@@ -197,7 +199,7 @@ trait GenTrees {
           }
         }
         else tree match {
-          case Select(qual, name) if !qual.symbol.isPackage && !qual.symbol.isPackageObject && qual.symbol != definitions.PredefModule =>
+          case Select(qual, name) if !qual.symbol.isPackage =>
             if (reifyDebug) println(s"reifying Select($qual, $name)")
             mirrorCall(nme.Select, reify(qual), reify(name))
           case SelectFromTypeTree(qual, name) =>