Incompatibility with PHP: child class can't change visibility of the trait method when the trait is used by a parent class

[Naktibalda]

Parent class uses the trait with protected method,
child class uses the same trait and changes visibility of method to public.
The method is public in PHP, but it is protected in HHVM.

<?php
trait t {
  protected function traitMethod() {
    return 1;
  }
}

abstract class p {
  use t; //parent class imports trait methods as is
  public function parentMethod() {
    return 1;
  }
}

class c extends p {
  use t {
    traitMethod as public; // child class changes visibility of method
  }

  public function classMethod() {
    return 1;
  }
}

$class = new \ReflectionClass(new c());

$methods = $class->getMethods(\ReflectionMethod::IS_PUBLIC);
var_dump($methods);

http://3v4l.org/S584c

Expected result:

array(3) {
  [0] =>
  class ReflectionMethod#2 (2) {
    public $name =>
    string(11) "classMethod"
    public $class =>
    string(1) "c"
  }
  [1] =>
  class ReflectionMethod#3 (2) {
    public $name =>
    string(12) "parentMethod"
    public $class =>
    string(1) "p"
  }
  [2] =>
  class ReflectionMethod#4 (2) {
    public $name =>
    string(11) "traitMethod"
    public $class =>
    string(1) "c"
  }
}

Actual result:

array(2) {
  [0]=>
  object(ReflectionMethod)#4 (2) {
    ["name"]=>
    string(11) "classMethod"
    ["class"]=>
    string(1) "c"
  }
  [1]=>
  object(ReflectionMethod)#5 (2) {
    ["name"]=>
    string(12) "parentMethod"
    ["class"]=>
    string(1) "p"
  }
}

[lexidor]

I am going over old issues on this repository, to see which ones apply to the current versions of hhvm.

This issue applies to running php code on hhvm. Hhvm nolonger supports running php code since hhvm version 4.0.0.

Using traits with as is not supported by Hack's trait model.

Naming[2102] Trait use as is a PHP feature that is unsupported in Hack
   --> file.hack
 24 |     traitMethod as public; // child class changes visibility of method
    |     ^^^^^^^^^^^

1 error found.