filter wp_unique_post_slug > doesn't pass original_slug

[preliot]

I'm using WordPress 5.0 Beta 4. Also noticed bug in earlier versions, such as 4.9.8.

Steps to recreate:

• Create new page / post
• Save post
• Edit post and change slug
• Filter 'wp_unique_post_slug' passes same value for $slug and $original_slug

Expected outcome:

• $slug = new slug
• $original_slug = old slug

[swissspidy]

Hi there and welcome to WordPress Trac!

The value of $original_slug isn't the old slug of the post, but the original value of the $slug at the beginning of the wp_unique_post_slug function, before it was modified.

When you edit the post in the editor, you tell WordPress your new slug. To make sure the new value is unique across posts, it's ran through wp_unique_post_slug. The old value of the slug is not involved in this process at all.

[preliot]

@swissspidy Thanks for the clarification.