SI-6793 Don't use super param accessors if inaccessible.

"Alias replacement" has been with us since 2005 (13c59adf9).

Given:

    package a {
      class C1(val v0: String)
      class C2(v1: String) extends a.C1(v1) { v1 }
    }

The reference to `v1` is rewritten as `C2.super.v0()`, and
no field is generated in `C2`.

(Oddly, this optimization doesn't seem to kick in if
these classes are in the empty package. That's probably
a distinct bug.)

However, this rewriting is done without consideration of
the accessibility of `v0` from `C2`.

This commit disables this optimization if there if `v0` is
not accessible.

1 files changed, 9 insertions, 0 deletions

diff --git a/test/files/run/t6793.scala b/test/files/run/t6793.scala
new file mode 100644
index 0000000000..0b1f1619af
--- /dev/null
+++ b/test/files/run/t6793.scala
@@ -0,0 +1,9 @@
+package a { class C1(private[a] val v0: String) }
+package b { class C2(v1: String) extends a.C1(v1) { def foo = v1 } }
+
+object Test extends App {
+  new b.C2("x")
+
+  val c2Fields = classOf[b.C2].getDeclaredFields
+  assert(c2Fields.size == 1, c2Fields.map(_.getName).toList)
+}