[wp-trac] [WordPress Trac] #64357: get_terms() no longer returns terms when "include" or "exclude" is set to 'all' or an empty value in WP 6.9

[WordPress Trac]

#64357: get_terms() no longer returns terms when "include" or "exclude" is set to
'all' or an empty value in WP 6.9
--------------------------+------------------------------
 Reporter:  ibachal       |       Owner:  (none)
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  Awaiting Review
Component:  Taxonomy      |     Version:  6.9
 Severity:  major         |  Resolution:
 Keywords:  has-patch     |     Focuses:
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Changes (by iflairwebtechnologies):

 * keywords:   => has-patch


Comment:

 **Summary:**
 This patch fixes a regression introduced in WordPress 6.9 where
 **get_terms()** fails to return any terms when the **include** or
 **exclude** arguments are passed as an empty value (**[], '', null**) or
 when **'include' => 'all' / 'exclude' => 'all'** is used. These values
 should result in no filtering, but in WP 6.9 they incorrectly produce no
 results.

 **Issue:**
 Previously, an empty **include** or **exclude** argument behaved as a no-
 op.
 After WP 6.9 changes in **WP_Term_Query::get_sql_for_clause()**, empty
 term sets were treated as invalid and returned **self::$no_results**. This
 broke several common usages including:

 - Calling get_terms(** [ 'include' => [] ]** )
 - Passing an empty string via REST or shortcode
 - Plugins using **'include' => 'all'** to indicate no filtering
 - Core internals expecting empty arrays to behave as wildcard matches

 **What this patch does:**
 -  Restores pre-6.9 behavior
 -  Ensures empty / invalid / "all" includes and excludes do NOT filter
 terms
 -  Prevents IN () and NOT IN () SQL from being generated
 -  Normalizes terms before generating SQL
 -  Maintains backward compatibility for all existing plugins, REST API,
 and shortcode usage

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Ticket URL: <https://core.trac.wordpress.org/ticket/64357#comment:2>
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