Quoting Jeff Eaton <
jeff@...>:
>
> *** If you can, at any point, call debug_backtrace() and see BOTH
> drupal functions AND functions from a non-GPL-compatible piece of
> software, the terms of the GPL are being violated. ***
>
Then any project that uses PHP and claims to be GPL is violating the
terms of the GPL as a rule of thumb. PHP isn't GPL licensed[1] and its
functions are viewable in a debug_backtrace().
[1]
http://www.php.net/license/3_01.txtEarnie