SI-9546 Fix regression in rewrite of case apply to constructor call

In SI-9425, I disabled the rewrite of `CaseClass.apply(x)` to
`new CaseClass(x)` if the constructor was was less accessible
than the apply method. This solved a problem with spurious
"constructor cannot be accessed" errors during refchecks for
case classes with non-public constructors.

However, for polymorphic case classes, refchecks was persistent,
and even after refusing to transform the `TypeApply` within:

    CaseClass.apply[String]("")

It *would* try again to transform the enclosing `Select`, a
code path only intended for monomorphic case classes. The tree has
a `PolyType`, which foiled the newly added accessibility check.

I've modified the call to `isSimpleCaseApply` from the transform
of `Select` nodes to exclude polymorphic apply's from being
considered twice.

1 files changed, 13 insertions, 0 deletions

diff --git a/test/files/run/t9546.scala b/test/files/run/t9546.scala
new file mode 100644
index 0000000000..7016881084
--- /dev/null
+++ b/test/files/run/t9546.scala
@@ -0,0 +1,13 @@
+package foo {
+  case class Opt[A] private[foo](val get: A) extends AnyVal
+  object Opt {
+    def mkOpt = Opt("")
+  }
+}
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    foo.Opt.mkOpt
+  }
+}
+