Some more improvement on the error messages whe...

Some more improvement on the error messages when @tailrec fails. Now it
gives a sensible message if the recursive target is actually a supertype
of this, rather than saying the call is not in tail position. No review.

1 files changed, 26 insertions, 0 deletions

diff --git a/test/files/neg/tailrec-2.scala b/test/files/neg/tailrec-2.scala
new file mode 100644
index 0000000000..4388815a06
--- /dev/null
+++ b/test/files/neg/tailrec-2.scala
@@ -0,0 +1,26 @@
+sealed abstract class Super[+A] {
+  def f[B >: A](mem: List[B]) : List[B]
+}
+// This one should fail, target is a supertype
+class Bop1[+A](val element: A) extends Super[A] {
+  @annotation.tailrec final def f[B >: A](mem: List[B]): List[B] = (null: Super[A]).f(mem)
+}
+// These succeed
+class Bop2[+A](val element: A) extends Super[A] {
+  @annotation.tailrec final def f[B >: A](mem: List[B]): List[B] = (null: Bop2[A]).f(mem)
+}
+object Bop3 extends Super[Nothing] {
+  @annotation.tailrec final def f[B](mem: List[B]): List[B] = (null: Bop3.type).f(mem)
+}
+class Bop4[+A](val element: A) extends Super[A] {
+  @annotation.tailrec final def f[B >: A](mem: List[B]): List[B] = Other.f[A].f(mem)
+}
+
+object Other {
+  def f[T] : Bop4[T] = error("")
+}
+
+object Bop {
+  def m1[A] : Super[A] = error("")
+  def m2[A] : Bop2[A] = error("")
+}
\ No newline at end of file