Ticket #37489: 37489-1.patch

src/wp-includes/query.php

@@ -3018 +3018 @@
                         }
                 }
 
+                if ( ! empty( $orderby ) and $orderby == "$wpdb->posts.post_date " . $q['order'] ) {
+                        $orderby = "$wpdb->posts.post_date " . $q['order'].  ", $wpdb->posts.ID " . $q['order'];
+                }
+
                 // Order search results by relevance only when another "orderby" is not specified in the query.
                 if ( ! empty( $q['s'] ) ) {
                         $search_orderby = '';

tests/phpunit/tests/query/results.php

@@ -718 +718 @@
                 $feed_comment = $this->q->next_comment();
                 $this->assertEquals( $comment_id, $feed_comment->comment_ID );
         }
+
+
+        public function test_posts_order_for_same_date() {
+                $this->factory->post->create_many( 100, array(
+                        'post_date' => '2016-01-01 00:00:00'
+                ) );
+
+                $expected = array_map( array( $this, 'get_post_id' ), $this->q->query( array() ) );
+                $actual   = array_map( array( $this, 'get_post_id' ), $this->q->query( array(
+                        'post_status' => array(
+                                'private',
+                                'publish'
+                        )
+                ) ) );
+                $this->assertSame( $expected, $actual );
+        }
+
+        /**
+         * @param WP_Post $post
+         * @return int
+         */
+        public function get_post_id( $post ) {
+                return $post->ID;
+        }
 }