Suppose the arrays below:

$arr1 = [
    'aa' => 0,
    'bb' => 5,
    'cc' => 0,
    'dd' => 2,
];

$arr2 = [
    'bb' => 5,
    'cc' => 7,
    'dd' => 2,
];

I need an elegant, one-liner, that will add the values of the second array to the values of the first array with the same keys.

Something like this:

foreach ( $arr1 as $key => $val ) {
    if ( isset( $arr2[$key] ) ) $arr1[$key] = $val + $arr2[$key];
}

but more elegant, and preferably one-liner.

Example: https://onlinephp.io/c/0bc42