Explicilty passing default value for escape in SplFileObject::fgetcsv changes outcome

Description

The following code:

<?php

$file = new SplFileObject('php://memory', 'rw+');

$file->fwrite("foo;bar;baz");
$file->seek(0);

$file->setCsvControl(';', "\n");

while (!$file->eof()) {
    $line = $file->fgetcsv(escape: '\\');
    var_dump($line);
}

Resulted in this output:

array(1) {
  [0]=>
  string(11) "foo;bar;baz"
}

But I expected this output instead:

array(3) {
  [0]=>
  string(3) "foo"
  [1]=>
  string(3) "bar"
  [2]=>
  string(3) "baz"
}

For context, I am currently working on migrating a codebase from 8.2 to 8.4, and thought the safest option to keep existing behavior for fgetcsv calls would be to explicitly provide the current value of the default parameter, considering it will change in the next major version. I understand WHY it was implemented like this, but it is still a weird outcome. Ideally, the paramters for the method fgetcsv should be nullable, and default to null instead, so that the behavior is consistent with the way user land PHP functions and methods with default values for parameters work.

PHP Version

PHP 8.4.16 (cli) (built: Jan 13 2026 01:36:09) (NTS)
Copyright (c) The PHP Group
Built by https://github.com/docker-library/php
Zend Engine v4.4.16, Copyright (c) Zend Technologies
    with Zend OPcache v8.4.16, Copyright (c), by Zend Technologies

Operating System

No response

从 SplFileObject::fgetcsv 入口点开始，使用显式传入的转义值通过 setCsvControl(';', "\n") 重现该示例。调查 nullable 参数是否可以使省略的默认值和显式指定的默认值保持一致，然后验证 CSV 是否被解析为所请求的三个字段。