Documentation for `add_meta_boxes` hook is incorrect

[opr18]

Related ticket: https://core.trac.wordpress.org/ticket/43229 that seems was solved a while ago, but has since changed back.

[The documentation for this hook](https://core.trac.wordpress.org/browser/tags/6.8.3/src/wp-admin/includes/meta-boxes.php#L1714) states that $post will be a WP_Post however in these locations it is not

• https://core.trac.wordpress.org/browser/tags/6.8.3/src/wp-admin/edit-link-form.php#L37
• https://core.trac.wordpress.org/browser/tags/6.8.3/src/wp-admin/edit-form-comment.php#L257
• https://core.trac.wordpress.org/browser/tags/6.8.3/src/wp-admin/includes/meta-boxes.php#L1683

I think some possible resolutions here would be:

• Update the docs to loosen the type of the second param being passed to the hook
• Fix instances where the second param to the hook is not a WP_Post

[soyebsalar01]

The hook is too old and too widely used to be refactored without breaking plugins, so explicitly documenting:
we can add the one line so User might not confuse.

@param WP_Post | WP_Comment | stdClass $post

do_action( 'edit_form_after_title', $post, $title ) this hooks used in several admin screens it is fired with non-WP_Post types, for example:

Link editor -> passes a stdClass (legacy Link Manager structure)

Comment editor-> passes a WP_Comment

Some meta-box contexts -> might pass null or an incomplete object depending on screen

so @opr18 is right the docs expect $post to always be a WP_Post, which isn’t true. This creates fragile code, silent failures, type-hinting conflicts, confusion for people reading core docs.

[westonruter]

Update the docs to loosen the type of the second param being passed to the hook

This makes sense to me.

This patch updates the documentation for the add_meta_boxes_{$post_type} and add_meta_boxes hooks to correctly reflect that $post will not always be a WP_Post object.

Trac ticket: https://core.trac.wordpress.org/ticket/64251

[nikunj8866]

@opr18 I've added a comment in PR for a minor adjustment.

[westonruter]

In 61278:

Docs: Update meta box action documentation to more accurately reflect the possible object types.

In addition to a meta box being able to be added for a post, it can also be added for a comment or a link, or even nothing at all when on the Dashboard.

Props opr18, nikunj8866, soyebsalar01, westonruter.
See #64224.
Fixes #64251.