Implementations of isValueType and isNonValueType.

Restrictions regarding how non-value types can be used have
generally not been enforced explicitly, depending instead on
the fact that the compiler wouldn't attempt to use them in
strange ways like offering a method type as a type argument.
Since users can now create most types from scratch, it has
become important to enforce the restrictions in a more
direct fashion.

This was a lot harder than it probably should have been
because there are so many types which go unmentioned by the
specification.  Hopefully a useful exercise in any case.

1 files changed, 30 insertions, 0 deletions

diff --git a/test/files/run/fail-non-value-types.scala b/test/files/run/fail-non-value-types.scala
new file mode 100644
index 0000000000..d9aa5c01ca
--- /dev/null
+++ b/test/files/run/fail-non-value-types.scala
@@ -0,0 +1,30 @@
+import scala.reflect.runtime.universe._
+
+class ImaginaryCanBuildFrom[-From, -Elem, +To]
+class CompletelyIndependentList[+A] {
+  type Repr <: CompletelyIndependentList[A]
+  def map[B, That](f: A => B)(implicit cbf: ImaginaryCanBuildFrom[Repr, B, That]): That = ???
+  def distinct(): CompletelyIndependentList[A] = ???
+}
+
+object Test {
+  var failed = false
+  def expectFailure[T](body: => T): Boolean = {
+    try { val res = body ; failed = true ; println(res + " failed to fail.") ; false }
+    catch { case _: AssertionError => true }
+  }
+
+  /** Attempt to use a method type as a type argument - expect failure. */
+  def tcon[T: TypeTag](args: Type*) = appliedType(typeOf[T].typeConstructor, args.toList)
+
+  val map      = typeOf[CompletelyIndependentList[Int]].member("map": TermName).typeSignature
+  val distinct = typeOf[CompletelyIndependentList[Int]].member("distinct": TermName).typeSignature
+
+  def main(args: Array[String]): Unit = {
+    expectFailure(println(tcon[CompletelyIndependentList[Int]](map)))
+    expectFailure(tcon[CompletelyIndependentList[Int]](distinct))
+    println(map)
+    println(distinct)
+    if (failed) sys.exit(1)
+  }
+}