Shadowed references

In TypeAssigner#ensureAccible we sometimes pick an inherited public
member as the denotation of a NamedType instead of an inaccessible
private one. The problem is that both are denotations for the same type,
which caused a noDoubleBindings assert failure. We now solve this problem
by creating a "shadowed" named type to hold the inherited member.

The shadowed named type is distinguished by its name, which reads

    (inherited)originalName

In the future, we should make this more robust by using a general
tagging scheme to create shadowed names.

Another fix is about import symbols. They are now referenced with
NonMemberTermRefs. With this fix, the test suite passes with no
double def violations.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/dotty/tools/dotc/core/SymDenotations.scala b/src/dotty/tools/dotc/core/SymDenotations.scala
index 7762f61dd..dc76999f6 100644
--- a/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -684,7 +684,8 @@ object SymDenotations {
 
     /** The symbol, in class `inClass`, that is overridden by this denotation. */
     final def overriddenSymbol(inClass: ClassSymbol)(implicit ctx: Context): Symbol =
-      matchingSymbol(inClass, owner.thisType)
+      if ((this is Private) && (owner ne inClass)) NoSymbol
+      else matchingSymbol(inClass, owner.thisType)
 
     /** All symbols overriden by this denotation. */
     final def allOverriddenSymbols(implicit ctx: Context): Iterator[Symbol] =
@@ -731,6 +732,9 @@ object SymDenotations {
     override def termRefWithSig(implicit ctx: Context): TermRef =
       TermRef.withSig(owner.thisType, name.asTermName, signature, this)
 
+    def nonMemberTermRef(implicit ctx: Context): TermRef =
+      TermRef.withNonMemberSym(owner.thisType, name.asTermName, symbol.asTerm)
+
     /** The variance of this type parameter or type member as an Int, with
      *  +1 = Covariant, -1 = Contravariant, 0 = Nonvariant, or not a type parameter
      */