From 91167c488d23dfaec8cc8305a3178a0b0f67d976 Mon Sep 17 00:00:00 2001
From: Andrew Ozz <admin@laptoptips.ca>
Date: Wed, 6 Sep 2023 21:48:17 +0000
Subject: [PATCH] Editor: Prevent possibility of a fatal error when previewing
 block themes.

Ensures that preview callbacks attached to the `stylesheet` and `template` filters do not run before `pluggable.php` has been included. These callbacks need functionality from `pluggable.php`.

Props: scruffian, johnbillion, SergeyBiryukov, okat, okat.
Fixes: #59000.
Built from https://develop.svn.wordpress.org/trunk@56529


git-svn-id: http://core.svn.wordpress.org/trunk@56041 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/default-filters.php |  3 +++
 wp-includes/theme-previews.php  | 21 +++++++++++++++------
 wp-includes/version.php         |  2 +-
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/wp-includes/default-filters.php b/wp-includes/default-filters.php
index c08073326c..a3ea1537cb 100644
--- a/wp-includes/default-filters.php
+++ b/wp-includes/default-filters.php
@@ -532,6 +532,9 @@ add_action( 'admin_enqueue_scripts', '_wp_customize_loader_settings' );
 add_action( 'delete_attachment', '_delete_attachment_theme_mod' );
 add_action( 'transition_post_status', '_wp_keep_alive_customize_changeset_dependent_auto_drafts', 20, 3 );
 
+// Block Theme Previews.
+add_action( 'plugins_loaded', 'initialize_theme_preview_hooks', 1 );
+
 // Calendar widget cache.
 add_action( 'save_post', 'delete_get_calendar_cache' );
 add_action( 'delete_post', 'delete_get_calendar_cache' );
diff --git a/wp-includes/theme-previews.php b/wp-includes/theme-previews.php
index e8e4a6a8c8..d3f5c631c9 100644
--- a/wp-includes/theme-previews.php
+++ b/wp-includes/theme-previews.php
@@ -75,10 +75,19 @@ function wp_block_theme_activate_nonce() {
 	<?php
 }
 
-// Attaches filters to enable theme previews in the Site Editor.
-if ( ! empty( $_GET['wp_theme_preview'] ) ) {
-	add_filter( 'stylesheet', 'wp_get_theme_preview_path' );
-	add_filter( 'template', 'wp_get_theme_preview_path' );
-	add_action( 'init', 'wp_attach_theme_preview_middleware' );
-	add_action( 'admin_head', 'wp_block_theme_activate_nonce' );
+/**
+ * Add filters and actions to enable Block Theme Previews in the Site Editor.
+ *
+ * The filters and actions should be added after `pluggable.php` is included as they may
+ * trigger code that uses `current_user_can()` which requires functionality from `pluggable.php`.
+ *
+ * @since 6.3.2
+ */
+function initialize_theme_preview_hooks() {
+	if ( ! empty( $_GET['wp_theme_preview'] ) ) {
+		add_filter( 'stylesheet', 'wp_get_theme_preview_path' );
+		add_filter( 'template', 'wp_get_theme_preview_path' );
+		add_action( 'init', 'wp_attach_theme_preview_middleware' );
+		add_action( 'admin_head', 'wp_block_theme_activate_nonce' );
+	}
 }
diff --git a/wp-includes/version.php b/wp-includes/version.php
index e8b5f5be52..2dbf840a0e 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-alpha-56527';
+$wp_version = '6.4-alpha-56529';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.