Description:
------------
In PHP 7.2.0-dev, when extending ReflectionClass and overriding the newInstance() method, I am receiving a warning about an incompatible declaration (see actual result for warning message).

In PHP 5.6.30 and 7.1.3, I do not receive this warning. This is a possible BC break in 7.2.

This warning turned up in the PHP nightlies on Travis CI for packages depending on the goaop/parser-reflection library. See here for details: https://github.com/goaop/parser-reflection/issues/70

I have confirmed the problem locally using the following test script, tested against 5.6.30, 7.1.3, and 7.2.0-dev (built 2017-03-22 from master).

Test script:
---------------
<?php

class Foo {}

class MyReflectionClass extends \ReflectionClass
{
    public function newInstance($args = null)
    {
        return call_user_func_array('parent::newInstance', func_get_args());
    }
}

$fooReflected = new MyReflectionClass(Foo::class);
$fooInstance = $fooReflected->newInstance();

var_export($fooInstance);

Expected result:
----------------
$ php reflection-class-error.php
Foo::__set_state(array(
))

Actual result:
--------------
$ php reflection-class-error.php
PHP Warning:  Declaration of MyReflectionClass::newInstance($args = NULL) should be compatible with ReflectionClass::newInstance(...$args) in /Users/ramsey/Desktop/reflection-class-error.php on line 11

Warning: Declaration of MyReflectionClass::newInstance($args = NULL) should be compatible with ReflectionClass::newInstance(...$args) in /Users/ramsey/Desktop/reflection-class-error.php on line 11
Foo::__set_state(array(
))