SI-5604, selections on package objects.

[backport]
mkAttributedSelect, which creates a Select tree based on
a symbol, has been a major source of package object bugs,
because it has not been accurately identifying selections
on package objects.  When selecting foo.bar, if foo turns
out to be a package object, the created Select tree must be

  foo.`package`.bar

However mkAttributedSelect was only examining the owner of
the symbol, which means it would work if the package object
defined bar directly, but not if it inherited it.

1 files changed, 22 insertions, 3 deletions

diff --git a/src/reflect/scala/reflect/internal/TreeGen.scala b/src/reflect/scala/reflect/internal/TreeGen.scala
index ebf0998573..c1753fc5a1 100644
--- a/src/reflect/scala/reflect/internal/TreeGen.scala
+++ b/src/reflect/scala/reflect/internal/TreeGen.scala
@@ -172,10 +172,29 @@ abstract class TreeGen extends macros.TreeBuilder {
     if (qual.symbol != null && (qual.symbol.isEffectiveRoot || qual.symbol.isEmptyPackage))
       mkAttributedIdent(sym)
     else {
+      // Have to recognize anytime a selection is made on a package
+      // so it can be rewritten to foo.bar.`package`.name rather than
+      // foo.bar.name if name is in the package object.
+      // TODO - factor out the common logic between this and
+      // the Typers method "isInPackageObject", used in typedIdent.
+      val qualsym = (
+        if (qual.tpe ne null) qual.tpe.typeSymbol
+        else if (qual.symbol ne null) qual.symbol
+        else NoSymbol
+      )
+      val needsPackageQualifier = (
+           (sym ne null)
+        && qualsym.isPackage
+        && !sym.isDefinedInPackage
+      )
       val pkgQualifier =
-        if (sym != null && sym.owner.isPackageObjectClass && sym.effectiveOwner == qual.tpe.typeSymbol) {
-          val obj = sym.owner.sourceModule
-          Select(qual, nme.PACKAGE) setSymbol obj setType singleType(qual.tpe, obj)
+        if (needsPackageQualifier) {
+          // The owner of a symbol which requires package qualification may be the
+          // package object iself, but it also could be any superclass of the package
+          // object.  In the latter case, we must go through the qualifier's info
+          // to obtain the right symbol.
+          val packageObject = if (sym.owner.isModuleClass) sym.owner.sourceModule else qual.tpe member nme.PACKAGE
+          Select(qual, nme.PACKAGE) setSymbol packageObject setType singleType(qual.tpe, packageObject)
         }
         else qual