Reachability warnings could be better worded

[smarter]

scala> def foo(a: Int) = a match { case x: Int => x } 
1 |def foo(a: Int) = a match { case x: Int => x }
  |                                 ^
  |this will always yield true, since `class Int` is a subclass of `class Int`

The reason given is a tautology, It would make more sense to say something like "this case will always be taken because the scrutinee `a` has type Int".
Also, the highlighted position is the position of x, but it would be more intuitive to highlight the position of x: Int.