add tests from scala/test/files/{pos,neg}

with explicit Unit return type

1 files changed, 44 insertions, 0 deletions

diff --git a/tests/untried/pos/t2060.scala b/tests/untried/pos/t2060.scala
new file mode 100755
index 000000000..2c701150e
--- /dev/null
+++ b/tests/untried/pos/t2060.scala
@@ -0,0 +1,44 @@
+/* The problem here is that we cannot insert an implicit to
+ * add a polymorphic method which is then instantiated to the
+ * right type. When searching for the implicit in the `fails to compile
+ * line':
+ *
+ *   val failure = 1.0 + new Op[Int]
+ *
+ * we reduce the problem to finding a function from Double to
+ * {+: _ >: Op[Int] <: Any}, that is, a method which takes
+ * an argument which is an Op[Int] or a supertype thereof.
+ * Class Rich is not a subtype of this structural record, because
+ * polymorphic method instantiation is not contained in subtyping.
+ * That is: The method type [I](op : Op[I]): Op[I] is not a subtype
+ * of (Op[Int]): Op[Int].
+ * At present it is unclear whether this problem can be solved.
+ */
+object Test {
+  class Op[I];
+  class IntOp extends Op[Int];
+
+  class Rich(x : Double) {
+    def +       (op : IntOp): IntOp = op;
+    def +    [I](op : Op[I]): Op[I] = op;
+    def plus [I](op : Op[I]): Op[I] = op;
+  }
+
+  implicit def iToRich(x : Double) =
+    new Rich(x);
+
+  // fails to compile
+  val x = 1.0 + new Op[Int]
+
+  // works as expected --
+  //   problem isn't in adding new "+"
+  val a = 1.0 + new IntOp;
+
+  // works as expected --
+  //   problem isn't in binding type variable I
+  val b = 1.0 plus new Op[Int];
+
+  // works as expected --
+  //   problem isn't in using Rich.+[I](op : Op[I])
+  val c = iToRich(1.0) + new Op[Int];
+}