call_user_func special function optimization unsound with strict_types

Description

The following code:

<?php
declare(strict_types=1);

namespace Foo;

// strlen() will be called with strict_types=0, so this is legal.
var_dump(call_user_func('strlen', false));

// Called with strict_types=1
var_dump(\call_user_func('strlen', false));

Resulted in this output:

int(0)

Fatal error: Uncaught TypeError: strlen(): Argument #1 ($string) must be of type string, false given in /in/bcCZ4:10
Stack trace:
#0 /in/bcCZ4(10): strlen(false)
#1 {main}
  thrown in /in/bcCZ4 on line 10

But I expected this output instead:

Well, not sure, it should be consistent I suppose

PHP Version

8.3+

Operating System

No response

从提供的 PHP 8.3+ reproducer 开始，在 strict_types=1 下比较 namespaced 和 fully qualified 的 call_user_func 调用路径。跟踪 PHP 解释器中的特殊函数优化，然后统一行为，并为这两种调用添加覆盖测试。