Merge pull request #3005 from paulp/pr/7886

SI-7886 unsoundness in pattern matcher.

1 files changed, 22 insertions, 0 deletions

diff --git a/test/files/neg/t7886.scala b/test/files/neg/t7886.scala
new file mode 100644
index 0000000000..55d80a0a43
--- /dev/null
+++ b/test/files/neg/t7886.scala
@@ -0,0 +1,22 @@
+trait Covariant[+A]
+trait Contra[-A] { def accept(p: A): Unit }
+trait Invariant[A] extends Covariant[A] with Contra[A]
+
+case class Unravel[A](m: Contra[A], msg: A)
+
+object Test extends Covariant[Any] {
+  def g(m: Contra[Any]): Unit = m accept 5
+  def f(x: Any): Unit = x match {
+    case Unravel(m, msg) => g(m)
+    case _               =>
+  }
+  def main(args: Array[String]) {
+    f(Unravel[String](new Contra[String] { def accept(x: String) = x.length }, ""))
+  }
+}
+// java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
+//   at Test$$anon$1.accept(a.scala:18)
+//   at Test$.g(a.scala:13)
+//   at Test$.f(a.scala:15)
+//   at Test$.main(a.scala:18)
+//   at Test.main(a.scala)