[wp-trac] [WordPress Trac] #35031: wp_old_slug_redirect() in 4.4 redirecting existing posts

[WordPress Trac]

#35031: wp_old_slug_redirect() in 4.4 redirecting existing posts
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 Reporter:  douglsmith                           |       Owner:  pento
     Type:  defect (bug)                         |      Status:  assigned
 Priority:  normal                               |   Milestone:  4.4.1
Component:  Query                                |     Version:  4.4
 Severity:  critical                             |  Resolution:
 Keywords:  has-patch needs-unit-tests needs-    |     Focuses:
  testing                                        |
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Comment (by pento):

 So, here's a quick order of operations, so that I don't have to keep re-
 reading all of this:

 * From `wp-blog-header.php`, `wp()` is called, which calls `$wp->main()`.
 * `$wp->main()` sets up the query, which looks for the post that matches
 the slug.
 * `$wp->main()` then calls `$wp->handle_404()`, which will set `is_404()`
 to true when the page doesn't exist. It *doesn't* set it to true when the
 URL is a feed, because lol.
 * We go back to `wp-blog-header.php`, which loads `template-loader.php`,
 which does the `template_redirect` action, which `wp_old_slug_redirect()`
 is hooked into.

 Now, the important bit here is that part of the point of [34659] was to
 handle URL endpoints, like `/feed/`. Feeds don't have a 404, though, so we
 can't just re-add the `is_404()` check. Instead, feeds are handled more
 intelligently inside `wp_old_slug_redirect()`. We want to maintain that
 logic.

 Because we know if a post does or doesn't exist (as determined by
 `$wp->handle_404()`), then we know that, after checking `is_feed()`, and
 `is_404()` is not true, we're looking at a real post, and we shouldn't
 redirect.

 And so, we have [attachment:35031.2.diff].

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Ticket URL: <https://core.trac.wordpress.org/ticket/35031#comment:15>
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