Capture leak by parent boxed field

[noti0na1]

Compiler version

3.7.3-RC1-bin-SNAPSHOT-nonbootstrapped-git-42fdd76

Minimized code

import language.experimental.captureChecking
import annotation.constructorOnly
import caps.*

trait IO:
  def run(): Unit

case class Box[T](value: T)

def hideIO(io: IO^): IO =
  class LocalIOBox extends Box(io), IO:
    def run(): Unit = value.run()
  val pure: IO = new LocalIOBox
  pure

class IOBox(@constructorOnly io: IO^) extends Box(io), IO:
  def run(): Unit = value.run()

def hideIO2(io: IO^): IO =
  val pure: IO = new IOBox(io)
  pure

Output

Compile success

Expectation

The constructor of *IOBox should refine the parent field value and charge io to the capture set.