Description:
------------
The expected behaviour of RecursiveArrayIterator is that only leaf nodes will be iterated, but if an array is contained by reference, it is not traversed, instead it is returned by next().

Explicit use of RecursiveIteratorIterator::LEAVES_ONLY has no affect.

HHVM gives the expected result, see https://3v4l.org/up3me 


Test script:
---------------
function flatten(array $nestedArraysAndStrings){
    $flat=[];
    $iter = new RecursiveIteratorIterator(
        new RecursiveArrayIterator($nestedArraysAndStrings));
    foreach($iter as $leaf){ $flat[] = $leaf; }
    return join(NULL, $flat);
}

$noRefs = [[[['some']]],[' nested ']," items \n"];

$withRefs = []+$noRefs;
$wat = $noRefs[0];
$withRefs[0] = &$wat;

echo flatten($noRefs);
echo flatten($withRefs);

Expected result:
----------------
some nested  items 
some nested  items 

Actual result:
--------------
some nested  items 
Notice: Array to string conversion ... on line 8
Array nested  items