term_exists might fail if slugs are changed

[leogermani]

The steps to reproduce this are:

1. Create a term. For example: 'test 123'
2. Change its slug to something completely different. For example, from 'test-123' to 'something-else'
3. Now call the function term_exists() passing 'test 123' (with 2 empty spaces between test and 123) as the term name, along with the taxonomy.

You will notice that term_exists() will not find it.

However, if you try to add this same term, with the two spaces, wp_insert_term() won't allow it because it will detect it as a duplicate.

This issue I believe touches some bigger discussion around term_exists() because this function handles the term name string in a different way that wp_insert_term() does, which, in my opinion, creates an inconsistency.

I've seem some discussions around this on https://core.trac.wordpress.org/ticket/43345 and https://core.trac.wordpress.org/ticket/32248.

In this comment, @boonebgorges argues that "term_exists() is a low-level function. Character encoding should be handled by the function that calls term_exists()", but aknowledges the inconsistencies and says " In short: it's a mess, and I don't recommend using it - use get_term_by() instead."

In fact get_term_by() finds it.

So I guess the question is, shoud we touch term_exists() and make it find the same duplicates wp_insert_term() does?

[leogermani]

Just realized that get_term_by() is not a good replacement for term_exists() because it does not expect term parent as a parameter...

[boonebgorges]

See https://core.trac.wordpress.org/ticket/47099#comment:2. WP_Term_Query is a workaround for this limitation in term_exists(), and we should not touch term_exists() for compatibility reasons.

Thanks for the ticket :)