[wp-trac] [WordPress Trac] #60984: WP_Query is returning the two same post instead of one

[WordPress Trac]

#60984: WP_Query is returning the two same post instead of one
--------------------------+-----------------------------
 Reporter:  tremidkhar    |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Query         |    Version:  6.5
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 WP_Query is returning two same posts when hooked into `pre_get_post` with
 a certain condition.

 Steps to reproduce the issue

 - Add a hook into the `pre_get_post` with a condition for a certain post
 type.
 - Set the `post__in` query variable to a specific ID of the same post
 type.
 - Set the `posts_per_page` to 1

 I tested this using the `Query Loop` block, and it always rendered two
 same posts instead of one.

 The query block settings

 {{{
 <!-- wp:query
 {"queryId":148,"query":{"perPage":"1","pages":0,"offset":0,"postType":"quote","order":"desc","orderBy":"date","author":"","search":"","exclude":[],"sticky":"","inherit":false,"parents":[]},"align":"wide"}
 -->
 }}}

 The PHP `pre_get_posts` includes the hotfix for this issue.

 {{{#!php
 <?php
 <?php
 /**
  * Modifies the query for the Quote of the Day post type.
  *
  * @param WP_Query $query The WP_Query instance (passed by reference).
  *
  * @return void
  */
 function wporg_modify_quote_of_the_day_query( WP_Query $query ): void {

         if ( ! $query->is_home() || 'quote' !== $query->get( 'post_type' )
 ) {
                 return;
         }

         // Prevent infinite loops.
         remove_action( 'pre_get_posts', __FUNCTION__ );

         $daily_quote    = wporg_get_daily_quote(); // Custom function that
 return a WP_Post (quote CPT) instance.
         $daily_quote_id = $daily_quote instanceof WP_Post ?
 $daily_quote->ID : null;
         $query->set( 'post__in', array( $daily_quote_id ) );
         $query->set( 'posts_per_page', 1 );

         // Hotfix: Two quote CPTs are being displayed.
         $query->set( 'ignore_sticky_posts', true );

         // Re-add the action.
         add_action( 'pre_get_posts', __FUNCTION__ );
 }
 add_action( 'pre_get_posts', 'wporg_modify_quote_of_the_day_query' );
 }}}

 The issues seem to be in the `class-wp-query.php` file where the
 [https://github.com/WordPress/wordpress-
 develop/blob/f525e665b6ea6e88289d82cad5fc1dfac57db109/src/wp-includes
 /class-wp-query.php#L3499-L3516 sticky post is being processed]. Thus, the
 `post__in` is being applied twice in the query.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/60984>
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