Unexpected null returned by session_set_cookie_params

[YuanchengJiang]

Description

The following code:

<?php
var_dump(session_set_cookie_params(3600, "/foo"));
?>

Resulted in this output:

NULL

But I expected this output instead:

Fatal error: session_set_cookie_params(): Return value must be of type bool, null returned in Unknown on line 0

To reproduce:

-d "session.use_cookies=0" -d "zend_extension=/php-src/modules/opcache.so" -d "opcache.enable=1" -d "opcache.enable_cli=1" -d "opcache.jit=1205"

PHP Version

nightly

Operating System

ubuntu 22.04

[nielsdos]

I suppose you're doing differential fuzzing between JIT and interpreter? Interesting idea, I've thought about doing it as well some time ago but I never found or made the time to actually do so.
Anyway, the difference comes here from the fact that the JIT doesn't implement the debug arginfo checks, while the interpreter does. session_set_cookie_params shouldn't return NULL in the first place.

[YuanchengJiang]

So good you sense and find the first issue of differential fuzzing. Yes I am trying but not sure how interesting bugs can I find in this way. (trying to find incorrect results in addition to crashes).