Pass full post object to clean_post_cache()

[duck_]

So that we have the post type without having to get_post() in clean_post_cache() which can cause notices (#19690).

See #20460 for the same for clean_user_cache().

get_post() in clean_post_cache() isn't much of a problem. We just need to check the the result. If it's empty() then we can assume the post isn't cached.

The recommendation/documentation would be to pass an object though.

The second patch still contains a few calls that pass a variable called $post_id through instead of $post. Is that correct? (or can the variables be renamed to be better self-documenting)

Replying to GaryJ:

The second patch still contains a few calls that pass a variable called $post_id through instead of $post. Is that correct? (or can the variables be renamed to be better self-documenting)

Yes. I updated the clean_post_cache() to reflect that it can be int or object. This ticket should be "accept an object in clean_post_cache()" and not "unconditionally switch to passing objects". The only situation that the object is actually necessary is when the cache clean is called after a database delete query when we want the object for its post type so we can ensure that the $taxonomy_relationship cache is cleaned.

In [20569]:

Accept a post object in clean_post_cache(). Fixes #20486.

The post_type can then be accessed to properly clean the taxonomy relationships cache.
The full object is useful in situations when an ID might reference a post that has been
removed from the database (e.g. wp_delete_post()).