`ReflectionConstant::__toString()` with a string value with null bytes truncates output

[DanielEScherzer]

Description

The following code:

<?php

define('DEMO', "f\0oo");
$r = new ReflectionConstant('DEMO');
echo $r;
var_dump( $r->getValue() );

Resulted in this output:

Constant [ string DEMO ] { f }
string(4) "foo"

But I expected this output instead (with a null byte in the first "foo" the same way that there is in the second)

Constant [ string DEMO ] { foo }
string(4) "foo"

https://3v4l.org/Au101#v

PHP Version

8.4+

Operating System

No response

[DanielEScherzer]

Caused by

php-src/ext/reflection/php_reflection.c

Lines 618 to 620 in 119163a

	} else if (Z_TYPE_P(value) == IS_STRING) {
	smart_str_appends(str, Z_STRVAL_P(value));
	} else {

- smart_str_appends means that the smart string building will use strlen(), this should instead be smart_str_append with Z_STR_P

Already fixed on master in #21414, we just need to backport the reflection changes