This may be similar to bug 0001382.

The setup is as follows:

• PHPUnit runs selenium tests
• PHP-CLI server (php -S) runs code and dumps coverage (using https://github.com/giorgiosironi/phpunit-selenium) to file system
• At the end of a test, PHPUnit collects coverage data through the php server using https://github.com/giorgiosironi/phpunit-selenium/blob/master/PHPUnit/Extensions/SeleniumCommon/phpunit_coverage.php

One particular test runs fine, but when it's time to collect coverage, the CLI server always segfaults. There's a particular spot in the test where, if I skip the rest, everything works fine. The next step causes a form submission, which in turn makes the server run quite a bit of code.

Strangely, if I try to get the coverage information manually (through the server), it works fine. Maybe PHPUnit-Selenium sets

I'm running PHP-CLI (7.1.11-1-ubuntu0.17.10.1 and 7.1.14 built from source) and have tried xdebug 2.6.0, 2.5.5 and current master. I've had segfaults like these before after upgrading PHP, but up until now upgrading to the latest version of xdebug fixed that. Not this time, however.

How can I help debugging this? I can't create a minimal test case, but I am willing to set up an environment where we can run the code that causes the segfault.