[wp-trac] [WordPress Trac] #39984: wp_insert_term can return wrong ID when multiple existing terms are found with the same name but differnet parent

[WordPress Trac]

#39984: wp_insert_term can return wrong ID when multiple existing terms are found
with the same name but differnet parent
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 Reporter:  mikejolley                            |       Owner:
     Type:  defect (bug)                          |      Status:  new
 Priority:  normal                                |   Milestone:  4.8
Component:  Taxonomy                              |     Version:  trunk
 Severity:  normal                                |  Resolution:
 Keywords:  has-patch dev-feedback needs-testing  |     Focuses:
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Changes (by boonebgorges):

 * component:  General => Taxonomy
 * milestone:  Awaiting Review => 4.8


Comment:

 Thanks for the detailed report and the patch, @mikejolley. I've attached a
 second patch that includes a test demonstrating the problem and the fix.

 Regarding your point 2 - I would like to talk through what's happening
 here, since it seems like a change in behavior. I believe that your patch
 for 1 has turned up a bug, along the following lines:

 - It's possible for there to be more than one member of `$name_matches`,
 either because of accented characters (see the following block) or because
 of hierarchy branches like the one described in this ticket.
 - When no slug is provided to `wp_insert_term()` and there's a name match
 (in the relevant part of the taxonomy), we generally want to return an
 error - this is one of the legacy error conditions of `wp_insert_term()`
 - It's usually the case that the first member of the `$name_matches` array
 will have the non-prefixed slug. That is: under normal circumstances
 (entering category names from the Dashboard), WP is responsible for
 generating slugs; so the first 'Child' will get the slug `child`, the
 second will get `child-foo`, etc. Since the default sort order of
 `get_terms()` is by ID, `child` will practically always be first.
 - This means that the `$name_match->slug === $slug` condition on line 2066
 is usually met. But it's sorta coincidental that this works: if you first
 created 'Child' with the manual slug `child-foo` and then created a second
 'Child' with `child`, you'd surface the bug, independently of the
 hierarchy issue described in this ticket.

 Does that sound right to you? If so, there are really two bugs to fix
 here.

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Ticket URL: <https://core.trac.wordpress.org/ticket/39984#comment:2>
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