1 files changed, 27 insertions, 0 deletions
diff --git a/tests/pos/t7093.scala b/tests/pos/t7093.scala
new file mode 100644
index 000000000..287b7a78c
--- /dev/null
+++ b/tests/pos/t7093.scala
@@ -0,0 +1,27 @@
+object Test {
+
+  trait A[+X] {
+    protected[this] def f(x: X): X = x
+  }
+
+  trait B extends A[B] {
+    def kaboom = f(new B {})
+  }
+
+// protected[this] disables variance checking
+// of the signature of `f`.
+//
+// C's parent list unifies A[B] with A[C]
+//
+// The protected[this] loophole is widely used
+// in the collections, every newBuilder method
+// would fail variance checking otherwise.
+  class C extends B with A[C] {
+    override protected[this] def f(c: C) = c
+  }
+
+// java.lang.ClassCastException: B$$anon$1 cannot be cast to C
+//  at C.f(<console>:15)
+  new C().kaboom
+}
+