From efb6e805dad360b4e45ebbd587bf6f70b7fc66e9 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov@git.wordpress.org>
Date: Sat, 9 May 2020 12:24:31 +0000
Subject: [PATCH] Administration: Avoid a PHP 7.4 notice in `add_meta_box()`
 when attempting to re-add a previously removed box.

The logic for skipping previously removed meta boxes with the `core` priority should also apply to the `sorted` priority that is used when the boxes were manually reordered.

Add a unit test.

Props coolmann, franzarmas, SergeyBiryukov.
Fixes #50019.

git-svn-id: https://develop.svn.wordpress.org/trunk@47777 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-admin/includes/template.php            | 25 +++++++++++--------
 .../phpunit/tests/admin/includesTemplate.php  | 21 +++++++++++++++-
 2 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/src/wp-admin/includes/template.php b/src/wp-admin/includes/template.php
index 168dc3bc07..b0fb03cb18 100644
--- a/src/wp-admin/includes/template.php
+++ b/src/wp-admin/includes/template.php
@@ -1063,16 +1063,18 @@ function add_meta_box( $id, $title, $callback, $screen = null, $context = 'advan
 				continue;
 			}
 
-			// If a core box was previously added or removed by a plugin, don't add.
-			if ( 'core' === $priority ) {
-				// If core box previously deleted, don't add.
-				if ( false === $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ] ) {
-					return;
-				}
+			// If a core box was previously removed, don't add.
+			if ( ( 'core' === $priority || 'sorted' === $priority )
+				&& false === $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ]
+			) {
+				return;
+			}
 
+			// If a core box was previously added by a plugin, don't add.
+			if ( 'core' === $priority ) {
 				/*
-				 * If box was added with default priority, give it core priority to
-				 * maintain sort order.
+				 * If the box was added with default priority, give it core priority
+				 * to maintain sort order.
 				 */
 				if ( 'default' === $a_priority ) {
 					$wp_meta_boxes[ $page ][ $a_context ]['core'][ $id ] = $wp_meta_boxes[ $page ][ $a_context ]['default'][ $id ];
@@ -1080,13 +1082,14 @@ function add_meta_box( $id, $title, $callback, $screen = null, $context = 'advan
 				}
 				return;
 			}
+
 			// If no priority given and ID already present, use existing priority.
 			if ( empty( $priority ) ) {
 				$priority = $a_priority;
 				/*
-				* Else, if we're adding to the sorted priority, we don't know the title
-				* or callback. Grab them from the previously added context/priority.
-				*/
+				 * Else, if we're adding to the sorted priority, we don't know the title
+				 * or callback. Grab them from the previously added context/priority.
+				 */
 			} elseif ( 'sorted' === $priority ) {
 				$title         = $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ]['title'];
 				$callback      = $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ]['callback'];
diff --git a/tests/phpunit/tests/admin/includesTemplate.php b/tests/phpunit/tests/admin/includesTemplate.php
index ea656c81e8..a944615b8d 100644
--- a/tests/phpunit/tests/admin/includesTemplate.php
+++ b/tests/phpunit/tests/admin/includesTemplate.php
@@ -57,7 +57,7 @@ class Tests_Admin_includesTemplate extends WP_UnitTestCase {
 	public function test_remove_meta_box() {
 		global $wp_meta_boxes;
 
-		// Add a meta boxes to remove.
+		// Add a meta box to remove.
 		add_meta_box( 'testbox1', 'Test Metabox', '__return_false', $current_screen = 'post' );
 
 		// Confirm it's there.
@@ -108,6 +108,25 @@ class Tests_Admin_includesTemplate extends WP_UnitTestCase {
 		$this->assertFalse( $wp_meta_boxes['attachment']['advanced']['default']['testbox1'] );
 	}
 
+	/**
+	 * @ticket 50019
+	 */
+	public function test_add_meta_box_with_previously_removed_box_and_sorted_priority() {
+		global $wp_meta_boxes;
+
+		// Add a meta box to remove.
+		add_meta_box( 'testbox1', 'Test Metabox', '__return_false', $current_screen = 'post' );
+
+		// Remove the meta box.
+		remove_meta_box( 'testbox1', $current_screen, 'advanced' );
+
+		// Attempt to re-add the meta box with the 'sorted' priority.
+		add_meta_box( 'testbox1', null, null, $current_screen, 'advanced', 'sorted' );
+
+		// Check that the meta box was not re-added.
+		$this->assertFalse( $wp_meta_boxes[ $current_screen ]['advanced']['default']['testbox1'] );
+	}
+
 	/**
 	 * Test calling get_settings_errors() with variations on where it gets errors from.
 	 *