PHP 7.3 compact(): Undefined variable: limits in class-wp-comment-query.php on line 853

[Andy Schmidt]

4.9.10 with PHP 7.3
compact() now requires all parameters to have existing variables.

PHP 7.3 was released in 2018, it is recommended version by WordPress -- so there should no longer be any lingering syntax notices.

[Andy Schmidt]

Obviously - short of a proper logic fix, this patch can be used in front of
compact( array() )
constructs.

<?php
                $pieces = array( 'fields', 'join', 'where', 'orderby', 'limits', 'groupby' );
                // patch starts: 
                foreach( $pieces as $item ) {
                        if ( isset( $$item ) )
                                continue;        // variable already defined and non-null.
                        $$item = null;           // (Re)define variable in case missing, or already null.
                }

[swissspidy]

Hi @andy-schmidt, thanks for your report.

Would you be able to create a patch file with your suggested change? See ​https://make.wordpress.org/core/handbook/contribute/ for documentation about how to create patches using Git or Subversion.

[earnjam]

WordPress 5.0 was released around the same time as PHP 7.3, and was the first version with designated PHP 7.3 support.

I'm not against this per se, but I'm not sure if backporting PHP compatibility updates to older WP versions is something we typically do. I'd lean toward closing this, but I defer to those with more experience in this area.

[jorbin]

Duplicate of #44416.

This was fixed in [43819]. 5.0 is the first version that supported PHP 7.3. WordPress 4.9 is now 3 versions behind, I would encourage you to update to the latest version.