Different behaviors between AnyVal/AnyRef case classes with private/protected constructors.

[scabug]

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scala> case class PrivateConstructorVal private (val underlying: String) extends AnyVal
defined class PrivateConstructorVal

scala> case class ProtectedConstructorVal protected (val underlying: String) extends AnyVal
defined class ProtectedConstructorVal

scala> case class PrivateConstructorRef private (val underlying: String)
defined class PrivateConstructorRef

scala> case class ProtectedConstructorRef protected (val underlying: String)
defined class ProtectedConstructorRef

scala> PrivateConstructorVal("")
res0: PrivateConstructorVal = PrivateConstructorVal()

scala> ProtectedConstructorVal("")
<console>:10: error: constructor ProtectedConstructorVal in class ProtectedConstructorVal cannot be accessed in object $iw
 Access to protected constructor ProtectedConstructorVal not permitted because
 enclosing object $iw is not a subclass of 
 class ProtectedConstructorVal where target is defined
              ProtectedConstructorVal("")
              ^

scala> PrivateConstructorRef("")
res2: PrivateConstructorRef = PrivateConstructorRef()

scala> ProtectedConstructorRef("")
<console>:10: error: constructor ProtectedConstructorRef in class ProtectedConstructorRef cannot be accessed in object $iw
 Access to protected constructor ProtectedConstructorRef not permitted because
 enclosing object $iw is not a subclass of 
 class ProtectedConstructorRef where target is defined
              ProtectedConstructorRef("")
              ^

I don't know which behavior is correct, but I guess they could behave the same.

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-8491?orig=1
Reporter: @Atry
Affected Versions: 2.10.3

[som-snytt]

That was then:

➜  snips cat t8491.scala

case class V private (s: String) extends AnyVal
case class W protected (s: String) extends AnyVal
case class X private (s: String)
case class Y protected (s: String)

object Test extends App {
  println {(
    V("v"),
    W("w"),
    X("x"),
    Y("y")
  )}
}
➜  snips scalac -d /tmp t8491.scala
t8491.scala:10: error: constructor W in class W cannot be accessed in object Test
 Access to protected constructor W not permitted because
 enclosing object Test is not a subclass of
 class W where target is defined
    W("w"),
    ^
t8491.scala:11: error: constructor X in class X cannot be accessed in object Test
    X("x"),
    ^
t8491.scala:12: error: constructor Y in class Y cannot be accessed in object Test
 Access to protected constructor Y not permitted because
 enclosing object Test is not a subclass of
 class Y where target is defined
    Y("y")
    ^
three errors found
➜  snips scalac -version
Scala compiler version 2.10.7 -- Copyright 2002-2017, LAMP/EPFL

This was also then:

➜  snips sdk use scala 2.11.12

Using scala version 2.11.12 in this shell.
➜  snips scalac -d /tmp t8491.scala
➜  snips

This is now:

➜  snips sdk use scala 3.1.1

Using scala version 3.1.1 in this shell.
➜  snips scalac -d /tmp t8491.scala
-- Error: t8491.scala:9:4 ----------------------------------------------------------------------------------------------
9 |    V("v"),
  |    ^
  |    method apply cannot be accessed as a member of V.type from module class Test$.
-- Error: t8491.scala:11:4 ---------------------------------------------------------------------------------------------
11 |    X("x"),
   |    ^
   |    method apply cannot be accessed as a member of X.type from module class Test$.
2 errors found
➜  snips

This is also now:

➜  snips sdk use scala 2.13.8

Using scala version 2.13.8 in this shell.
➜  snips scalac -Xsource:3 -d /tmp t8491.scala
t8491.scala:9: error: method apply in object V cannot be accessed as a member of object V from object Test
error after rewriting to V.<apply: error>
possible cause: maybe a wrong Dynamic method signature?
    V("v"),
    ^
t8491.scala:11: error: method apply in object X cannot be accessed as a member of object X from object Test
error after rewriting to X.<apply: error>
possible cause: maybe a wrong Dynamic method signature?
    X("x"),
    ^
2 errors

scala/scala#7702