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

SplFileObject::fgetcsv のエントリポイントから開始し、エスケープ値を明示的に渡して setCsvControl(';', "\n") を使用する例を再現します。nullable パラメータによって、省略したデフォルト値と明示的に指定したデフォルト値を一貫させられるかを調査し、その後、CSV が要求された 3 つのフィールドにパースされることを確認します。