[wp-trac] [WordPress Trac] #54795: Bootstrap: Move navigation post type hooks to `admin-filters.php`

[WordPress Trac]

#54795: Bootstrap: Move navigation post type hooks to `admin-filters.php`
----------------------------+-----------------------------
 Reporter:  dlh             |      Owner:  (none)
     Type:  defect (bug)    |     Status:  new
 Priority:  normal          |  Milestone:  Awaiting Review
Component:  Bootstrap/Load  |    Version:  trunk
 Severity:  normal          |   Keywords:
  Focuses:                  |
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 WordPress 5.9 adds some new actions and filters to `default-filters.php`
 into hooks that typically run only in the admin, such as `admin_head` and
 `admin_footer-widgets.php`.

 I can see that there are plenty of other similar examples that predate
 5.9, and, generally, it's not a big deal.

 However, three of these new hooks go one step further by adding callbacks
 that are themselves only loaded in the admin:

 {{{
 add_action( 'use_block_editor_for_post_type',
 '_disable_block_editor_for_navigation_post_type', 10, 2 );
 add_action( 'edit_form_after_title',
 '_disable_content_editor_for_navigation_post_type' );
 add_action( 'edit_form_after_editor',
 '_enable_content_editor_for_navigation_post_type' );
 }}}

 There is precedent, too, for adding admin-only callbacks in `default-
 filters.php`, but the implications are more noticeable: On PHP 8+, a fatal
 error will occur if those hooks fire in a non-admin context and attempt to
 call an undefined function.

 I hear you asking: Isn't somebody doing it wrong if those hooks run
 outside the admin? Probably. Did I, myself, manually apply the
 `use_block_editor_for_post_type` filter in a plugin? I sure did, and I'll
 fix the plugin :)

 Still, I was on the fence about whether adding admin-only functions to
 `default-filters.php` is also not quite doing it right. It risks creating
 new warnings or fatal errors without serving an obvious (to me) purpose
 for core. [32653] described `admin-filters.php` as "[containing] functions
 that won't work outside of admin context." So, I thought I would open a
 ticket to ask:

 1. Should the new default actions and filters in 5.9 that call admin-only
 functions be moved to `admin-filters.php`? (They seemed to work as
 expected there when I tested.)
 2. Should the three admin-only functions instead be globally included, not
 admin-only?

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Ticket URL: <https://core.trac.wordpress.org/ticket/54795>
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