diff --git a/src/wp-includes/post.php b/src/wp-includes/post.php
index deb215e17d..f621f456ba 100644
a
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b
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function _publish_post_hook( $post_id ) { |
6821 | 6821 | * |
6822 | 6822 | * @since 3.1.0 |
6823 | 6823 | * |
6824 | | * @param int|WP_Post $post Post ID or post object. Defaults to global $post. |
| 6824 | * @param int|WP_Post|null $post Optional. Post ID or post object. Defaults to global $post. |
6825 | 6825 | * @return int|false Post parent ID (which can be 0 if there is no parent), or false if the post does not exist. |
6826 | 6826 | */ |
6827 | | function wp_get_post_parent_id( $post ) { |
| 6827 | function wp_get_post_parent_id( $post = null ) { |
6828 | 6828 | $post = get_post( $post ); |
6829 | 6829 | if ( ! $post || is_wp_error( $post ) ) { |
6830 | 6830 | return false; |