SI-4859 Don't elide qualifiers when selecting nested modules.

Otherwise we fail to throw in:

   {???; Predef}.DummyImplicit.dummyImplicit

We still elide the initialization of `Outer` in `Outer.Inner.foo`
as before, although that seems a little dubious to me.

In total, we had to change RefChecks, Flatten, and GenICode
to effect this change. A recently fixed bug in tail call elimination
was also due to assuming that the the qualifier of a Select node
wasn't worthy of traversal.  Let's keep a close eye out for more
instances of this problem.

1 files changed, 29 insertions, 0 deletions

diff --git a/test/files/run/t4859.scala b/test/files/run/t4859.scala
new file mode 100644
index 0000000000..6d223f2179
--- /dev/null
+++ b/test/files/run/t4859.scala
@@ -0,0 +1,29 @@
+object O {
+  case class N()
+  object P
+}
+
+object Outer {
+  println("Outer")
+  object Inner {
+    println("Inner")
+    def i {
+      println("Inner.i")
+    }
+  }
+}
+
+object Test {
+  def main(args: Array[String]) {
+    Outer.Inner.i // we still don't initiialize Outer here (but should we?)
+
+    {println("About to reference Inner.i"); Outer}.Inner.i // Outer will be initialized.
+
+    {println("About to reference O.N"        ); O}.N
+
+    {println("About to reference O.N"        ); O}.N
+
+    {println("About to reference O.N.apply()"); O}.N.apply()
+  }
+}
+