lampepfl/dotty — pull request #283 by odersky (2014-12-13 18:20:04+00:00)
Title: Disable implicit conversions between from `Null` and `Nothing`.

This is necessary to reject code like

val x: Boolean = null

Without the restriction, this code would typecheck and expand to

val x: Boolean = Predef.Boolean2boolean(null)

since `null` counts as a value of type `java.lang.Boolean`.

Closes #291. Review by @smarter