SI-8143 Fix bug with super-accessors / dependent types

Super-accessors are generated as `DefDef`'s with `EmptyTree` as a
placeholder for the RHS. This is filled in later in `Mixin` in
`completeSuperAccessor`.

A change in `Uncurry` (SI-6443 / 493197f), however, converted this
to a `{ EmptyTree }`, which evaded the pattern match in mixin.

This commit adds a special case to the dependent method treatment
in Uncurry to avoid generating redundant blocks.

1 files changed, 24 insertions, 0 deletions

diff --git a/test/files/pos/t8138.scala b/test/files/pos/t8138.scala
new file mode 100644
index 0000000000..b980930955
--- /dev/null
+++ b/test/files/pos/t8138.scala
@@ -0,0 +1,24 @@
+
+class U {
+  trait Transformer {
+    def transform(a: Tree): Tree = ???
+  }
+  trait Tree
+}
+
+object Test {
+  def m(u: U) = {
+    class C extends u.Transformer {
+      override def transform(t: u.Tree): u.Tree = {
+        null match {
+          case _ =>
+            // crashes in GenICode:
+            // error: Unknown type: <notype>, <notype> [class scala.reflect.internal.Types$NoType$, class scala.reflect.internal.Types$NoType$] TypeRef? false
+            (y: Any) => super.transform(???)
+            null
+        }
+        ???
+      }
+    }
+  }
+}