unused post_types show in search and cannot be deleted

[thomask]

when you create some posts with custom post_type and then delete the custom post_type definition, the posts are still visible in search (typicaly title+excerpt, but they throw 404 when clicked).

Second problem is, that you cannot delete them (only via e.g. phpmyadmin) - first it is hard to find them, but even when you know the ID a try to direct edit it, it shows "you are not allowed to edit this item", even when I am administrator with all rights.

The issue, we're discussing, is that for both post types and stati, we loop through post types that are registered with exclude_from_search = true, and remove them from search.

Instead, it should start from nothing and add only registered post types where exclude_from_search = false.

First pass to *include* the registered post types that are included in search rather than excluding post types that are not included in the search...that really sounds confusing.

(In [14419]) White list instead of black list post types when searching. Props sivel. fixes #13183