Fix improper use of the hooks API

[azaozz]

Using lambda functions as callbacks for add_action() and add_filter() is not supported as it breaks part of the WP Hooks API. It prevents the removal of such callbacks, remove_action() and remove_filter() stop working.

It seems there are few cases of such breakage in core:

• ​https://github.com/WordPress/wordpress-develop/blob/master/src/wp-admin/edit-form-blocks.php#L32
• ​https://github.com/WordPress/wordpress-develop/blob/master/src/wp-admin/options-privacy.php#L21
• ​https://github.com/WordPress/wordpress-develop/blob/master/src/wp-admin/privacy-policy-guide.php#L20
• ​https://github.com/WordPress/wordpress-develop/blob/master/src/wp-includes/script-loader.php#L2448
• ​https://github.com/WordPress/wordpress-develop/blob/master/src/wp-includes/sitemaps/class-wp-sitemaps-renderer.php#L254

(and possibly other).

Generally hooks should be added to either wp-admin/includes/admin-filters.php or wp-includes/default-filters.php as much as possible. It's also acceptable to add them from functions or "template" files. However hooks should never be added from "include" files (for security reasons), and lambda callbacks are not acceptable.

[azaozz]

Related: #51506, #49264, #53616, #50117

• https://core.trac.wordpress.org/changeset/50996/trunk/src/wp-admin/edit-form-blocks.php
• https://core.trac.wordpress.org/changeset/50161/trunk/src/wp-admin/options-privacy.php
• https://core.trac.wordpress.org/changeset/50161/trunk/src/wp-admin/privacy-policy-guide.php
• https://core.trac.wordpress.org/changeset/51471/trunk/src/wp-includes/script-loader.php
• https://core.trac.wordpress.org/browser/trunk/src/wp-includes/sitemaps/class-wp-sitemaps-renderer.php?rev=48072

Would probably be good to add some docs explaining how things work to avoid this in the future.

This PR converts the lambda functions that adds body classes in the following pages:

• wp-admin/post-new.php and wp-admin/post-new.php?post_type=page - ​https://github.com/WordPress/wordpress-develop/blob/master/src/wp-admin/edit-form-blocks.php#L32
• wp-admin/options-privacy.php - ​https://github.com/WordPress/wordpress-develop/blob/master/src/wp-admin/options-privacy.php#L21
• wp-admin/options-privacy.php?tab=policyguide ​https://github.com/WordPress/wordpress-develop/blob/master/src/wp-admin/privacy-policy-guide.php#L20

New filters are as follows

• body_class_edit_form_blocks
• body_class_options_privacy

Trac ticket: https://core.trac.wordpress.org/ticket/54028

[donmhico]

Nice catch @azaozz!

I've converted the filters in the following files:

• ​https://github.com/WordPress/wordpress-develop/blob/master/src/wp-admin/edit-form-blocks.php#L32
• ​https://github.com/WordPress/wordpress-develop/blob/master/src/wp-admin/options-privacy.php#L21
• ​https://github.com/WordPress/wordpress-develop/blob/master/src/wp-admin/privacy-policy-guide.php#L20

I'll try to work on the other files as time permits.

[hellofromTonya]

#54367 was marked as a duplicate.

[hellofromTonya]

With 5.9 Beta 1 happening in less than 4 hours, moving this ticket to 6.0.

[johnregan3]

@donmhico I have time to finish up this ticket if that's okay with you.

I've found a few other instances that need to be updated as well.
Here's the list I have so far (including instances mentioned above)

add_filter()
​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-admin/edit-form-blocks.php#L32
​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-admin/options-privacy.php#L21
​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-admin/privacy-policy-guide.php#L20
​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/script-loader.php#L2460
​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/sitemaps/class-wp-sitemaps-renderer.php#L254

(This one is in a docblock, but it's a bad example)
​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/theme.php#L1999

add_action()
​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/block-supports/layout.php#L194
​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/block-supports/elements.php#L76

[johnregan3]

Just an update to note I'm currently working on this ticket.

[chesio]

Here's one more instance of lambda function hooked to add_action: ​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/block-supports/duotone.php#L459-L467

Trac ticket: https://core.trac.wordpress.org/ticket/54028

Fixes/updates hooks using lambda functions.
The list below is taken from the trac ticket.

Note that the two unaddressed issues below are lambda functions using use to pass data into the filter, and it would take serious work to correct these issues that may be beyond the scope of this ticket, which I believe is generally to "clean things up." I'm definitely open to advice on how to approach fixing these.

add_filter()

• ​x [wp-admin/edit-form-blocks.php#L36]
• ​x [wp-admin/poptions-privacy.php#L21]
• ​x [wp-admin/privacy-policy-guide.php#L20]
• ​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/script-loader.php#L2492 [wp-includes/script-loader.php#L2492]
• ​x [wp-includes/sitemaps/class-wp-sitemaps-renderer.php#L254]

Bad example in docblock

• [x] ​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/theme.php#L1999

add_action()

• ​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/block-supports/duotone.php#L550 [wp-includes/block-supports/duotone.php#L550]

Mentioned in ticket, but no longer valid

• _​wp-includes/block-supports/layout.php#L194_
• _​wp-includes/block-supports/elements.php#L76_

Props to @donmhico and ​their PR.

[johnregan3]

PR issued for discussion. @azaozz @donmhico

[audrasjb]

I requested changes on a few Docblocks issues in the above PR, otherwise the patch looks good to me

[johnregan3]

Diff of what is included in github PR 2401

[costdev]

Per the discussion in the bug scrub, I'm moving this ticket to Future Release as this still needs architectural decisions before it can proceed.

[spacedmonkey]

Some more examples

​https://github.com/WordPress/wordpress-develop/blob/b316c8b25fc71920d89ee37ee26609a77b2a305a/src/wp-includes/script-loader.php#L3526-L3528