--TEST--
Bug #42177 (Warning "array_merge_recursive(): recursion detected" comes again...)
--FILE--
<?php

$a1 = array( 'key1' => 1, 'key3' => 2 );
$a2 = array();
$a1 = array_merge_recursive( $a1, $a2 );
$a1 = array_merge_recursive( $a1, $a2 );
unset( $a1, $a2 );

$a1 = array();
$a2 = array( 'key1' => 1, 'key3' => 2 );
$a1 = array_merge_recursive( $a1, $a2 );
$a1 = array_merge_recursive( $a1, $a2 );
unset( $a1, $a2 );

$a1 = array();
$a2 = array( 'key1' => &$a1 );
$a1 = array_merge_recursive( $a1, $a2 );
try {
    $a1 = array_merge_recursive( $a1, $a2 );
} catch (\Error $e) {
    echo $e->getMessage() . " on line " . $e->getLine() . "\n";
}
unset( $a1, $a2 );

$x = 'foo';
$y =& $x;
$a1 = array($x, $y, $x, $y);
$a2 = array( 'key1' => $a1, $x, $y );
$a1 = array_merge_recursive( $a1, $a2 );
$a1 = array_merge_recursive( $a1, $a2 );
unset( $a1, $a2 );

?>
--EXPECT--
Recursion detected on line 19