I think the bug I reported (https://bugs.xdebug.org/view.php?id=2306) might be related with this; in fact, in our webapp, we do get references to the superglobals at the very beginning of the request cycle.

However, in my case, there is not shutdown function registered, and the segfault happens only when the debugging session is not actually started.

I can trivially reproduce this. Thanks for the short and succint report!

This turned out to be a similar issue than 0002305 — at least it has the same cause.

I have made a PR: https://github.com/xdebug/xdebug/pull/986

Would you be able to check the xdebug_3_4 branch from Xdebug's Github (once it's merged)?

I also ran into this issue, using xdebug 3.4.0 on 8.3 and 8.4. Using xdebug latest master branch solved this issue. Thank you Derick, happy holidays.

Although this changes solves most issues, I have to add that this is not the only cause of segmentation faults in 3.4.0. This snippet of code still causes a segfault:

<?php
echo "bla";
$fasel = &$_GET;

set_exception_handler(static function () {
echo '1';
});

require_once '_non_existing_file';

I have checked out the xdebug_3_4 branch and added the compiled xdebug of a PHP 8.4. The problem can no longer be reproduced with this version.

This program makes use of the Zend Scripting Language Engine:
Zend Engine v4.4.1, Copyright (c) Zend Technologies with Zend OPcache v8.4.1, Copyright (c), by Zend Technologies with Xdebug v3.4.1-dev, Copyright (c) 2002-2024, by Derick Rethans

I can confirm https://bugs.xdebug.org/view.php?id=2307#c7124 with a similar variant:

--- test2.php
<?php
echo "a"b"; # PHP-Syntax-Error

--- test1.php
<?php
$get = &$_GET;
function bla(Throwable $exception) {
echo "fasel";
}
set_exception_handler("bla");
include "test2.php";

Calling test1.php with a PHP 8.4 and Xdebug v3.4.1-dev also returns a segmentation fault.

It seemed that I fixed a symptom, and not the actual issue, which is: Segmentation fault due to a superglobal being a reference

https://github.com/xdebug/xdebug/pull/987

I've merged the PR. It would be great if you could have a check/look again!

All seems fine with the last revision. Thank you Derick.