[wp-trac] [WordPress Trac] #56351: Shared terms will not apply properly to a post in WordPress 6.0

[WordPress Trac]

#56351: Shared terms will not apply properly to a post in WordPress 6.0
--------------------------+-----------------------------
 Reporter:  kaygee79      |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Taxonomy      |    Version:
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 Starting with WordPress 6.0, and with a databases that still as shared
 terms, only one taxonomy can be applied to a post.

 Having a term that belongs to multiple taxonomies e.g.


 {{{
 +---------+---------------+---------------+----------+
 | term_id | name          | slug          | taxonomy |
 +---------+---------------+---------------+----------+
 |     277 | TermSplitTest | termsplittest | category |
 |     277 | TermSplitTest | termsplittest | post_tag |
 +---------+---------------+---------------+----------+

 +------------------+---------+----------+-------------+--------+-------+
 | term_taxonomy_id | term_id | taxonomy | description | parent | count |
 +------------------+---------+----------+-------------+--------+-------+
 |              472 |     277 | category |             |      0 |     8 |
 |              277 |     277 | post_tag |             |      0 |     6 |
 +------------------+---------+----------+-------------+--------+-------+
 }}}

 A post will apply the term to only one taxonomy e.g. selecting this term
 as a category will apply this term as a post tag or vice versa. This
 change was introduced in: https://core.trac.wordpress.org/changeset/52921/


 With WordPress 5.9.x the `term_exists` function would return the correct
 `term_taxonomy_id`:


 {{{
 term_exists( 277, 'category' );
 Array
 (
     [term_id] => 277
     [term_taxonomy_id] => 472
 )

 term_exists( 277, 'post_tag' );
 Array
 (
     [term_id] => 277
     [term_taxonomy_id] => 277
 )
 }}}


 With WordPress 6.0.x `term_exists` returns the same `term_taxonomy_id`:


 {{{
 term_exists( 277, 'category' );
 Array
 (
     [term_id] => 277
     [term_taxonomy_id] => 277
 )

 term_exists( 277, 'post_tag' );
 Array
 (
     [term_id] => 277
     [term_taxonomy_id] => 277
 )
 }}}


 The term will be split if you re-save it in `wp-admin` using the
 `category` taxonomy. The same does not happen if you re-save the term in
 the `post_tag` taxonomy. Instead you get an error:

 [[Image(https://d.pr/i/Ll8FoF.png)]]

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/56351>
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