Cycle defense.

Notice when a typeref's info creates an obvious cycle, so we can see an
error instead of a stack overflow. Closes SI-5093, review by moors.

1 files changed, 3 insertions, 0 deletions

diff --git a/test/files/neg/t5093.scala b/test/files/neg/t5093.scala
new file mode 100644
index 0000000000..9cde364dee
--- /dev/null
+++ b/test/files/neg/t5093.scala
@@ -0,0 +1,3 @@
+class T {
+  def f[C[X] <: C[X]](l: C[_]) = l.x
+}