Avoid doing an extra call to cache/wpdb when post_id is not valid

[bor0]

While investigating an issue on WooCommerce.com, we discovered that some plugins invoke WP_Post::get_instance( -1 ).

Although one could argue this is a plugin-level problem, we noticed that WordPress still processes the request and unnecessarily performs calls to wp_cache_get and wpdb->get_row.

We propose adding a short-circuit to handle cases where post_id is negative, not just when it equals zero.

[bor0]

Props @akeda for the patch.

@SergeyBiryukov could use your input here as well. Thanks a ton 🙏

[SergeyBiryukov]

In 60654:

Posts, Post Types: Avoid an extra database query in WP_Post for a negative post ID.

Follow-up to [21559].

Props bor0, akeda, SergeyBiryukov.
Fixes #63850.

[bor0]

@SergeyBiryukov, I really admire your prompt actions.

I owe you a ton of beer and/or coffee, whichever your drink preference is.

Thank you!

[Howdy_McGee]

Created a new enhancement ticket for supporting Faux WP_Post Objects #64362