[JIT] Undefined to null coercion issues for return

[iluuu1994]

Description

<?php
function test($cond): ?int {
    if ($cond) {
        $i = 'foo';
    }
    return $i;
}

var_dump(test(false));
var_dump(test(false));

With tracing JIT:

php: ext/opcache/jit/zend_jit_trace.c:348: zend_jit_trace_type_to_info_ex: Assertion `info & (1 << type)' failed.

Termsig=6

With function JIT:

Fatal error: Uncaught TypeError: test(): Return value must be of type ?int, null returned in test.php:7

But I expected this output instead:

Warning: Undefined variable $i in %s on line %d

Warning: Undefined variable $i in %s on line %d
NULL

Warning: Undefined variable $i in %s on line %d

Warning: Undefined variable $i in %s on line %d
NULL

Currently, this should emit 4 warnings, due to #16495. That should be changed in the future. Anyway, that's not the issue.

@dstogov I can have a look if you want, but it's going to take me longer. 🙂

PHP Version

PHP 8.4

Operating System

No response