Relaxes a typer check which fails valid code wi...

Relaxes a typer check which fails valid code with NoCommonType. If the
instantiated types or type bounds do not conform, it tries normalizing
the type before throwing the exception. Closes #4553. I wrote this patch
with adriaan already, but bonus review by moors.

1 files changed, 11 insertions, 0 deletions

diff --git a/test/files/pos/bug4553.scala b/test/files/pos/bug4553.scala
new file mode 100755
index 0000000000..4eefe57b2b
--- /dev/null
+++ b/test/files/pos/bug4553.scala
@@ -0,0 +1,11 @@
+trait VectorLike[+T, +V[A] <: Vector[A]] {
+  def +[S, VResult[S] >: V[S]](v: VResult[S])
+}
+
+trait Vector[+T] extends VectorLike[T, Vector]
+trait ImmutableVector[T] extends Vector[T] with VectorLike[T, ImmutableVector]
+trait MutableVector[T] extends Vector[T] with VectorLike[T, MutableVector]
+
+object Test {
+  def f = (null: MutableVector[Int]) + (null: ImmutableVector[Int])
+}