1--TEST--
2FILTER_CALLBACK with explicit FILTER_REQUIRE_SCALAR
3--EXTENSIONS--
4filter
5--FILE--
6<?php
7function test($var) {
8    $callback = function ($var) {
9        return $var;
10    };
11    return filter_var($var, FILTER_CALLBACK, ['options' => $callback, 'flags' => FILTER_REQUIRE_SCALAR]);
12}
13var_dump(test('test'));
14var_dump(test(['test']));
15?>
16--EXPECT--
17string(4) "test"
18bool(false)
19