SI-6680 unsoundness in gadt typing.

Introduces -Xstrict-inference to deal with the significant
gap between soundness and what presently compiles. I'm hopeful
that it's TOO strict, because it finds e.g. 75 errors compiling
immutable/IntMap.scala, but it might be that bad.

1 files changed, 26 insertions, 0 deletions

diff --git a/test/files/neg/gadts2-strict.scala b/test/files/neg/gadts2-strict.scala
new file mode 100644
index 0000000000..54978b7712
--- /dev/null
+++ b/test/files/neg/gadts2-strict.scala
@@ -0,0 +1,26 @@
+// A copy of pos/gadts2, which must fail under -Xstrict-inference.
+object Test {
+
+  abstract class Number
+  case class MyInt(n: Int) extends Number
+  case class MyDouble(d: Double) extends Number
+
+  trait Term[a]
+  case class Cell[a](var x: a) extends Term[a]
+  final case class NumTerm(val n: Number) extends Term[Number]
+
+  def f[a](t: Term[a], c: Cell[a]) {
+    t match {
+      case NumTerm(n) => c.x = MyDouble(1.0)
+    }
+  }
+
+  val x: Term[Number] = NumTerm(MyInt(5))
+
+  def main(args: Array[String]) {
+    val cell = Cell[Number](MyInt(6))
+    Console.println(cell)
+    f[Number](new NumTerm(MyInt(5)), cell)
+    Console.println(cell)
+  }
+}