PHP warnings generated by wp_generate_tag_cloud

[tomdxw]

PHP Warning: min(): Array must contain at least one element in /var/vhost/xxxx/wp-includes/category-template.php on line 658
PHP Warning: max(): Array must contain at least one element in /var/vhost/xxxx/wp-includes/category-template.php on line 659

I'm not sure how to reproduce the bug but it can be fixed easily by replacing min( $counts ) with count( $counts ) > 0 ? min( $counts ) : 0 and replacing max( $counts ) with (count( $counts ) > 0 ? max( $counts ) : 0). Or by checking whether $counts is empty and returning early.

[desaiuditd]

Added patch for the issue reported.
Review needed.
27413.patch

[SergeyBiryukov]

Looks like the only way to trigger these warnings is to return an empty array in tag_cloud_sort filter:

add_filter( 'tag_cloud_sort', '__return_empty_array' );

This looks like a developer error, so the developer should see the warning.

If the goal is to remove the output, wp_generate_tag_cloud filter should be used instead:
tags/3.8.1/src/wp-includes/category-template.php#L694​

[desaiuditd]

Yeah, that's true. This is the outcome of an unexpected behavior. Though I think, it should be handled because even the developers should not be put into confusion with such unwanted warnings/errors. Even if someone is passing an empty array; that should not affect the default workflow i.e., generate tag cloud if there are tags or do not generate tag cloud if empty array is passed

[SergeyBiryukov]

Introduced in [11037].

I guess we could check the filtered value and return if it's empty, see 27413.2.patch​.

Also noticed that the function doesn't have a consistent return value, see #27487.

[desaiuditd]

Fair enough. +1

[nacin]

In 27709:

Gracefully fail in wp_generate_tag_cloud() when emptiness is returned from the tag_cloud_sort filter.

props SergeyBiryukov.
fixes #27413.