From 61234818aec15492f818659dc74b1108bc36f392 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov@git.wordpress.org>
Date: Sun, 16 Dec 2018 23:23:38 +0000
Subject: [PATCH] Block Editor: Hide the Custom Fields meta box option if that
 meta box has been removed.

Some plugins remove the Custom Fields meta box, particularly when they provide functionality that replaces it. The block editor would correctly not display this meta box in these circumstances, but it still showed the option to display or hide it.

Props pento, noisysocks.
Merges [43885] to trunk.
See #45282.

git-svn-id: https://develop.svn.wordpress.org/trunk@44244 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-admin/edit-form-blocks.php    | 68 +++++++++++++++-------------
 src/wp-admin/includes/meta-boxes.php |  6 ++-
 src/wp-admin/includes/template.php   |  3 +-
 3 files changed, 44 insertions(+), 33 deletions(-)

diff --git a/src/wp-admin/edit-form-blocks.php b/src/wp-admin/edit-form-blocks.php
index 7b80b304f1..2ee0ba988a 100644
--- a/src/wp-admin/edit-form-blocks.php
+++ b/src/wp-admin/edit-form-blocks.php
@@ -19,8 +19,9 @@ if ( ! defined( 'ABSPATH' ) ) {
  * @global WP_Post      $post
  * @global string       $title
  * @global array        $editor_styles
+ * @global array        $wp_meta_boxes
  */
-global $post_type, $post_type_object, $post, $title, $editor_styles;
+global $post_type, $post_type_object, $post, $title, $editor_styles, $wp_meta_boxes;
 
 if ( ! empty( $post_type_object ) ) {
 	$title = $post_type_object->labels->edit_item;
@@ -296,36 +297,6 @@ if ( $is_new_post && ! isset( $editor_settings['template'] ) && 'post' === $post
 	}
 }
 
-$init_script = <<<JS
-( function() {
-	window._wpLoadBlockEditor = new Promise( function( resolve ) {
-		wp.domReady( function() {
-			resolve( wp.editPost.initializeEditor( 'editor', "%s", %d, %s, %s ) );
-		} );
-	} );
-} )();
-JS;
-
-
-/**
- * Filters the settings to pass to the block editor.
- *
- * @since 5.0.0
- *
- * @param array   $editor_settings Default editor settings.
- * @param WP_Post $post            Post being edited.
- */
-$editor_settings = apply_filters( 'block_editor_settings', $editor_settings, $post );
-
-$script = sprintf(
-	$init_script,
-	$post->post_type,
-	$post->ID,
-	wp_json_encode( $editor_settings ),
-	wp_json_encode( $initial_edits )
-);
-wp_add_inline_script( 'wp-edit-post', $script );
-
 /**
  * Scripts
  */
@@ -358,6 +329,41 @@ do_action( 'enqueue_block_editor_assets' );
 require_once( ABSPATH . 'wp-admin/includes/meta-boxes.php' );
 register_and_do_post_meta_boxes( $post );
 
+// Check if the Custom Fields meta box has been removed at some point.
+$core_meta_boxes = $wp_meta_boxes[ $current_screen->id ]['normal']['core'];
+if ( ! isset( $core_meta_boxes['postcustom'] ) || ! $core_meta_boxes['postcustom'] ) {
+	unset( $editor_settings['enableCustomFields'] );
+}
+
+/**
+ * Filters the settings to pass to the block editor.
+ *
+ * @since 5.0.0
+ *
+ * @param array   $editor_settings Default editor settings.
+ * @param WP_Post $post            Post being edited.
+ */
+$editor_settings = apply_filters( 'block_editor_settings', $editor_settings, $post );
+
+$init_script = <<<JS
+( function() {
+	window._wpLoadBlockEditor = new Promise( function( resolve ) {
+		wp.domReady( function() {
+			resolve( wp.editPost.initializeEditor( 'editor', "%s", %d, %s, %s ) );
+		} );
+	} );
+} )();
+JS;
+
+$script = sprintf(
+	$init_script,
+	$post->post_type,
+	$post->ID,
+	wp_json_encode( $editor_settings ),
+	wp_json_encode( $initial_edits )
+);
+wp_add_inline_script( 'wp-edit-post', $script );
+
 require_once( ABSPATH . 'wp-admin/admin-header.php' );
 ?>
 
diff --git a/src/wp-admin/includes/meta-boxes.php b/src/wp-admin/includes/meta-boxes.php
index a3e61acd4f..0f175892d6 100644
--- a/src/wp-admin/includes/meta-boxes.php
+++ b/src/wp-admin/includes/meta-boxes.php
@@ -1463,7 +1463,11 @@ function register_and_do_post_meta_boxes( $post ) {
 	}
 
 	if ( post_type_supports( $post_type, 'custom-fields' ) ) {
-		add_meta_box( 'postcustom', __( 'Custom Fields' ), 'post_custom_meta_box', null, 'normal', 'core', array( '__back_compat_meta_box' => true ) );
+		$args = array(
+			'__back_compat_meta_box'             => ! (bool) get_user_meta( get_current_user_id(), 'enable_custom_fields', true ),
+			'__block_editor_compatible_meta_box' => true,
+		);
+		add_meta_box( 'postcustom', __( 'Custom Fields' ), 'post_custom_meta_box', null, 'normal', 'core', $args );
 	}
 
 	/**
diff --git a/src/wp-admin/includes/template.php b/src/wp-admin/includes/template.php
index 65c268b3e8..6dbd0d24ab 100644
--- a/src/wp-admin/includes/template.php
+++ b/src/wp-admin/includes/template.php
@@ -1161,7 +1161,8 @@ function do_meta_boxes( $screen, $context, $object ) {
 					}
 
 					$i++;
-					$hidden_class = in_array( $box['id'], $hidden ) ? ' hide-if-js' : '';
+					// get_hidden_meta_boxes() doesn't apply in the block editor.
+					$hidden_class = ( ! $screen->is_block_editor() && in_array( $box['id'], $hidden ) ) ? ' hide-if-js' : '';
 					echo '<div id="' . $box['id'] . '" class="postbox ' . postbox_classes( $box['id'], $page ) . $hidden_class . '" ' . '>' . "\n";
 					if ( 'dashboard_browser_nag' != $box['id'] ) {
 						$widget_title = $box['title'];