The flag 'JSON_UNESCAPED_LINE_TERMINATORS' seems to be useless

[JoeHorn]

Description

The following code:

<?php
$strs = [
  'str1' => "Line1\nLine2",
  'str2' => "Line1\r\nLine2",
  'str3' => 'Line1' . PHP_EOL . 'Line2',
];
foreach ($strs as $k => $v) {
  echo "** {$k} **" . PHP_EOL . $v . PHP_EOL . PHP_EOL;
}

echo '** json_encoded **' . PHP_EOL . json_encode(
  $strs,
  JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_LINE_TERMINATORS
) . PHP_EOL . PHP_EOL;

Resulted in this output:

** str1 **
Line1
Line2

** str2 **
Line1
Line2

** str3 **
Line1
Line2

** json_encoded **
{"str1":"Line1\nLine2","str2":"Line1\r\nLine2","str3":"Line1\nLine2"}

But I expected this output instead:

** str1 **
Line1
Line2

** str2 **
Line1
Line2

** str3 **
Line1
Line2

** json_encoded **
{"str1":"Line1
Line2","str2":"Line1
Line2","str3":"Line1
Line2"}

PHP Version

PHP 8.3.6 (cli) (built: Mar 20 2026 02:32:55) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.3.6, Copyright (c) Zend Technologies
    with Zend OPcache v8.3.6, Copyright (c), by Zend Technologies

Operating System

Ubuntu 24.04

[LamentXU123]

Thanks for reporting. Not so sure, but I think this is more like an expected feature.

Now, according to RFC 8259, all control chars, from U+0000 to U+001F MUST be escaped.

All Unicode characters may be placed within the
quotation marks, except for the characters that MUST be escaped:
quotation mark, reverse solidus, and the control characters (U+0000
through U+001F).

So it is normal that \r\n is printed. The JSON_UNESCAPED_LINE_TERMINATORS is only designed to fit into the ES2019 features. So, it only works on U+2028 and U+2029. Just my 2 cents.