Interested in solving this too.
The line in question causing problems is init.php line 61:
add_action('widgets_init', create_function('', 'return register_widget("MCI_Footnotes_Widget_ReferenceContainer");'));
My favored solution is to make the add_action callable a function definition:
add_action('widgets_init', function() {
return register_widget("MCI_Footnotes_Widget_ReferenceContainer");
});
This requires support for PHP 5.3+ (the plugin shows compatibility currently with WP 3.9+, which claims to run on PHP 5.2.4+. Don’t know if that makes a difference; I’m betting the plugin already uses some features for later versions of PHP). @markcheret is this something you can put in place on a release to make compatibility with PHP 7.2+ better?
~Dan
