Refactor: Prepare WHERE clause for adjacent post queries in get_adjacent_post function.

This change enhances the SQL query preparation by introducing a separate variable for the WHERE clause, improving readability and maintainability. The version number for the ID-based fallback feature has been updated to 6.9.0.

Author: ramonjd

src/wp-includes/link-template.php

@@ -1964,6 +1964,9 @@ function get_adjacent_post( $in_same_term = false, $excluded_terms = '', $previo
 	 */
 	$join = apply_filters( "get_{$adjacent}_post_join", $join, $in_same_term, $excluded_terms, $taxonomy, $post );
 
+	// Prepare the where clause for the adjacent post query.
+	$where_prepared = $wpdb->prepare( "WHERE (p.post_date $op %s OR (p.post_date = %s AND p.ID $op %d)) AND p.post_type = %s $where", $current_post_date, $current_post_date, $post->ID, $post->post_type ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- $op is a string literal, either '<' or '>'.
+
 	/**
 	 * Filters the WHERE clause in the SQL for an adjacent post query.
 	 *
@@ -1977,15 +1980,15 @@ function get_adjacent_post( $in_same_term = false, $excluded_terms = '', $previo
 	 *
 	 * @since 2.5.0
 	 * @since 4.4.0 Added the `$taxonomy` and `$post` parameters.
-	 * @since n.e.x.t Adds ID-based fallback for posts with identical dates in adjacent post queries.
+	 * @since 6.9.0 Adds ID-based fallback for posts with identical dates in adjacent post queries.
 	 *
 	 * @param string       $where          The `WHERE` clause in the SQL.
 	 * @param bool         $in_same_term   Whether post should be in the same taxonomy term.
 	 * @param int[]|string $excluded_terms Array of excluded term IDs. Empty string if none were provided.
 	 * @param string       $taxonomy       Taxonomy. Used to identify the term used when `$in_same_term` is true.
 	 * @param WP_Post      $post           WP_Post object.
 	 */
-	$where = apply_filters( "get_{$adjacent}_post_where", $wpdb->prepare( "WHERE (p.post_date $op %s OR (p.post_date = %s AND p.ID $op %d)) AND p.post_type = %s $where", $current_post_date, $current_post_date, $post->ID, $post->post_type ), $in_same_term, $excluded_terms, $taxonomy, $post );
+	$where = apply_filters( "get_{$adjacent}_post_where", $where_prepared, $in_same_term, $excluded_terms, $taxonomy, $post );
 
 	/**
 	 * Filters the ORDER BY clause in the SQL for an adjacent post query.
@@ -2001,7 +2004,7 @@ function get_adjacent_post( $in_same_term = false, $excluded_terms = '', $previo
 	 * @since 2.5.0
 	 * @since 4.4.0 Added the `$post` parameter.
 	 * @since 4.9.0 Added the `$order` parameter.
-	 * @since n.e.x.t Adds ID sort to ensure deterministic ordering for posts with identical dates.
+	 * @since 6.9.0 Adds ID sort to ensure deterministic ordering for posts with identical dates.
 	 *
 	 * @param string $order_by The `ORDER BY` clause in the SQL.
 	 * @param WP_Post $post    WP_Post object.