Make val field in implicit class private

[olafurpg]

I just observed that the val field in an implicit class is accesible as an extension method

scala> implicit class XtensionString(val str: String) extends AnyVal {
     |   def doubled = str + str
     | }
defined class XtensionString

scala> "message".str
res0: String = message

A workaround to prevent this is to make the field private

scala> implicit class XtensionString(private val str: String) extends AnyVal

It would be nice to have a scalafix rule to automatically fix this.

Context: https://gitter.im/scala/contributors?at=5a4e57685355812e57502b5b

[LeonardMeyer]

I took a stab at this. Can't really test right now because of #547 but will do.

I do have one question though : Why does Ctor.Primary of ScalaMeta has a List[List[Term.Param]] ? Why two levels ?

[olafurpg]

Cool @LeonardMeyer ! I will try to take a look at #547 in the coming week.

Primary constructors can be curried which are represented as List[List[Term.Param]]

@ show(q"class A(a: Int)(b: String)".ctor)
Ctor.Primary(
  List(),
  _,
  List(
    List(Term.Param(List(), Term.Name("a"), Some(Type.Name("Int")), None)),
    List(Term.Param(List(), Term.Name("b"), Some(Type.Name("String")), None))
  )
)

[LeonardMeyer]

I literally realized this right before coming back here 😄 By the way, even private won't help with something like this :

class A(val str: String) {
  def doubled: String = str + str
}

implicit class B(override val str: String) extends A(str)

"test".str  //visible