diff.php

<?php

function foo(array ...$as): array
{
	assert(count($as) >= 2);

	return array_diff_uassoc(array_shift($as), ...$as, fn($a, $b) => $a - $b);
}

You could do this:

function foo(array ...$as): array
{
    assert(count($as) >= 2);
    
    return call_user_func_array('array_diff_uassoc', [...$as, fn($a, $b) => $a <=> $b]);
}

True! Thanks for the suggestion!

Or call it repeatedly, each time with two arrays from $as. Could even use array_reduce for that:

function foo(array ...$as): array
{
    assert(count($as) >= 2);
    
    return array_reduce(
        array_slice($as, 1, null, true),
        fn($carry, $item) => array_diff_uassoc($carry, $item, fn($a, $b) => $a <=> $b),
        $as[0]
    );
}