Merge pull request #3005 from paulp/pr/7886

SI-7886 unsoundness in pattern matcher.

1 files changed, 18 insertions, 0 deletions

diff --git a/test/files/neg/run-gadts-strict.scala b/test/files/neg/run-gadts-strict.scala
new file mode 100644
index 0000000000..041d10d4bd
--- /dev/null
+++ b/test/files/neg/run-gadts-strict.scala
@@ -0,0 +1,18 @@
+// A copy of run/gadts.scala, which must fail under -Xstrict-inference.
+abstract class Term[T]
+case class Lit(x: Int) extends Term[Int]
+case class Succ(t: Term[Int]) extends Term[Int]
+case class IsZero(t: Term[Int]) extends Term[Boolean]
+case class If[T](c: Term[Boolean],
+                 t1: Term[T],
+                 t2: Term[T]) extends Term[T]
+
+object Test extends App {
+  def eval[T](t: Term[T]): T = t match {
+    case Lit(n)        => n
+    case Succ(u)       => eval(u) + 1
+    case IsZero(u)     => eval(u) == 0
+    case If(c, u1, u2) => eval(if (eval(c)) u1 else u2)
+  }
+  println(eval(If(IsZero(Lit(1)), Lit(41), Succ(Lit(41)))))
+}