Inconsistent behavior of `filter_var()` with `FILTER_REQUIRE_ARRAY` and `default` option for non-array inputs

Description

The following code:

<?php

var_dump(filter_var("a", FILTER_VALIDATE_INT, ['flags' => FILTER_REQUIRE_ARRAY, 'options' => ['default' => 'Failed']]));
var_dump(filter_var([1], FILTER_VALIDATE_INT, ['flags' => FILTER_REQUIRE_ARRAY, 'options' => ['default' => 'Failed']]));
var_dump(filter_var(["a"], FILTER_VALIDATE_INT, ['flags' => FILTER_REQUIRE_ARRAY, 'options' => ['default' => 'Failed']]));
var_dump(filter_var("a", FILTER_VALIDATE_INT, ['options' => ['default' => 'Failed']]));

Resulted in this output:

bool(false)
array(1) {[0]=> int(1)}
array(1) {[0]=> string(6) "Failed"}
string(6) "Failed"

But I expected this output instead:

array(1) {[0]=> string(6) "Failed"} or string(6) "Failed"
array(1) {[0]=> int(1)}
array(1) {[0]=> string(6) "Failed"}
string(6) "Failed"

Since the documentation says:

default, value to return if the filter fails

I was expecting to get at least some form of Failed.

PHP Version

PHP 8.3

Operating System

Windows 11

首先，在 PHP 8.3 上复现 issue 中的四个 filter_var() 示例，并将输出与文档中说明的默认行为进行比较。跟踪 filter_var() 的实现，以及针对 FILTER_REQUIRE_ARRAY 和默认选项的现有测试；当所选择的行为对标量输入和数组输入保持一致，并且有回归测试覆盖时，即视为完成。