From 2a686addf02c4cac0fac0ff7b949ff7ffbcbf5f8 Mon Sep 17 00:00:00 2001
From: hellofromTonya <hellofromTonya@git.wordpress.org>
Date: Tue, 11 Jan 2022 16:00:01 +0000
Subject: [PATCH] Editor: Fix enqueueing additional styles in
 `wp_enqueue_block_style()` to print only when blocks render.

In a block theme, additional block styles registered using the `wp_enqueue_block_style` function should only get printed when the block exists on a page. However, they currently always get rendered.

This commit is a backport from Gutenberg that fixes the issue by printing the styles when a block renders.

Follow-up to [52069].

Props poena, aristath, Mamaduka.
Fixes #54787.
Built from https://develop.svn.wordpress.org/trunk@52556


git-svn-id: http://core.svn.wordpress.org/trunk@52146 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/blocks.php  | 26 +++++++++++++++++++++++++-
 wp-includes/version.php |  2 +-
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/wp-includes/blocks.php b/wp-includes/blocks.php
index 0f34aac1df..d6d73bdfe8 100644
--- a/wp-includes/blocks.php
+++ b/wp-includes/blocks.php
@@ -1254,7 +1254,31 @@ function wp_enqueue_block_style( $block_name, $args ) {
 
 	$hook = did_action( 'wp_enqueue_scripts' ) ? 'wp_footer' : 'wp_enqueue_scripts';
 	if ( wp_should_load_separate_core_block_assets() ) {
-		$hook = "render_block_$block_name";
+		/**
+		 * Callback function to register and enqueue styles.
+		 *
+		 * @param string $content The block content.
+		 * @param array  $block   The full block, including name and attributes.
+		 * @return string Block content.
+		 */
+		$callback_separate = static function( $content, $block ) use ( $block_name, $callback ) {
+			if ( ! empty( $block['blockName'] ) && $block_name === $block['blockName'] ) {
+				return $callback( $content );
+			}
+			return $content;
+		};
+
+		/*
+		 * The filter's callback here is an anonymous function because
+		 * using a named function in this case is not possible.
+		 *
+		 * The function cannot be unhooked, however, users are still able
+		 * to dequeue the stylesheets registered/enqueued by the callback
+		 * which is why in this case, using an anonymous function
+		 * was deemed acceptable.
+		 */
+		add_filter( 'render_block', $callback_separate, 10, 2 );
+		return;
 	}
 
 	/*
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 36220f08e2..2443ce9388 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.0-alpha-52555';
+$wp_version = '6.0-alpha-52556';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.