Unable to use @specialized annotation on a class with a private primary constructor

[OndrejSpanel]

reproduction steps

using Scala 2.13.3, 2.12.12

class Cls[@specialized(Float) A] private () {
  override def clone(): Cls[A] = new Cls[A]()
}

problem

The code does not compile, the error returned is:

constructor Cls in class Cls cannot be accessed in class Cls$mcF$sp
 Access to protected constructor Cls not permitted because
 prefix type Cls[Float] does not conform to
 class Cls$mcF$sp where the access takes place
  override def clone(): Cls[A] = new Cls[A]()

Changing the constructor from private to protected does not help.

The code is compiled without error using dotty 0.27.0-RC1

[Jasper-M]

The code is compiled without error using dotty 0.27.0-RC1

I suppose dotty just ignores the @specialized annotation?

[OndrejSpanel]

This was already described in http://aleksandar-prokopec.com/2013/11/03/specialization-quirks.html:

When you instantiate an anonymous class inside a specialized class and the anonymous class accesses private members of the surrounding specialized class, you might get a compiler error message telling you that the member cannot be accessed.

Solution – just make the problematic members package-private