The type hierarchy chart in the "Explicit Nulls" document doesn't include the `Matchable` type

[ShapelessCat]

The type hierarchy chart in this Explicit Nulls page doesn't include the Matchable type.
The description is also a little bit out of date, and it doesn't mention the relation between Null and Matchable after applying the -Yexplicit-nulls compiler flag.

[noti0na1]

I don't think -Yexplicit-nulls will affect Null and Matchable significantly.

Null will just become the direct subtype of Any and Matchable.

I need to update the diagram and description.

[bishabosha]

I don't think -Yexplicit-nulls will affect Null and Matchable significantly.

Null will just become the direct subtype of Any and Matchable.

Are the following examples bugs?

$ scala -Yexplicit-nulls
scala> def foo[T <: Matchable](t: T) = t match { case t: Null => () }
1 |def foo[T <: Matchable](t: T) = t match { case t: Null => () }
  |                                               ^
  |        this case is unreachable since type T and class Null are unrelated

scala> def foo[T <: Matchable](t: T) = t match { case null => () }                                               
1 |def foo[T <: Matchable](t: T) = t match { case null => () }
  |                                               ^^^^
  |Values of types Null and T
  |
  |where:    T is a type in method foo with bounds >: (?1 : Null) and <: Matchable
  | cannot be compared with == or !=

scala> def foo[T <: Matchable](t: T) = t match { case t => println(s"got $t") }                                     
def foo[T <: Matchable](t: T): Unit

scala> foo(null)
got null

[noti0na1]

@bishabosha I think they are bugs.

It seems we didn't add Matchable to the parent type of Null when Matchable was introduced. I will fix this soon.

[olhotak]

The diagram is an image generated using graphviz. Could the graphviz source of the diagram be stored in git somewhere? What would be the best place? Does the markdown processor used to generate the docs support graphviz?