Allow abstract type members in objects.

[nicolasstucki]

No description provided.

[DarkDimius]

why?

[nicolasstucki]

Because scalac allows it.

Furthermore it is already possible to have abstract types in objects by defining it in a trait

trait A {
 type T <: Any
}

object B extends A // B has the abstract type T

In this case it would be simpler to define it as

object B {
  type T  <: Any
}

[odersky]

Do we have a test that checks that bounds of abstract type members are non-empty, i.e. lower bound <: upper bound? In that case, LGTM

[nicolasstucki]

The error of the bound >: Any <: Nothing is the reason for the cannot be instantiated error, the full message is quite clear on the source of the issue.

[sjrd]

See here for a concrete use case: https://github.com/sjrd/scala-unboxed-option/blob/4222ec1d95982ac7a5912c1d06eacb8f7b09554f/src/main/scala/uoption/package.scala#L23
Also in this case it's even in a package object