Disallow taking a class tag of Nothing or Null.

It seems in most cases this leads to weird behavior and cause
confusing error messages later.

It also means we cannot create an Array[Nothing], except by
passing the classtag explicitly.

1 files changed, 5 insertions, 0 deletions

diff --git a/tests/neg/undet-classtag.scala b/tests/neg/undet-classtag.scala
new file mode 100644
index 000000000..563596d14
--- /dev/null
+++ b/tests/neg/undet-classtag.scala
@@ -0,0 +1,5 @@
+object Test {
+  def f[T: reflect.ClassTag](x: T) = ???
+
+  f(???) // error: undetermined ClassTag
+}