From 43a8631882b552dba95bb8b59ab06c1dc49160dd Mon Sep 17 00:00:00 2001
From: Jorge Costa <jorgefilipecosta@git.wordpress.org>
Date: Wed, 16 Feb 2022 17:26:46 +0000
Subject: [PATCH] Script Loader: Load block support styles in the head for
 block themes.

The dynamic block styles for layout and elements should be loaded in the head for block themes. While that should also be the case for classic themes, the current mechanism we use (render_block) does not allow us to do that, hence, this PR doesn't change anything for them and will be loaded the body.

Props oandregal, youknowriad, wpsoul.
Fixes #55148.

git-svn-id: https://develop.svn.wordpress.org/trunk@52741 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/block-supports/elements.php | 14 ++---------
 src/wp-includes/block-supports/layout.php   | 12 +---------
 src/wp-includes/blocks.php                  | 26 +++++++++++++++++++++
 3 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/src/wp-includes/block-supports/elements.php b/src/wp-includes/block-supports/elements.php
index ceb8841ac1..4f09591227 100644
--- a/src/wp-includes/block-supports/elements.php
+++ b/src/wp-includes/block-supports/elements.php
@@ -46,7 +46,7 @@ function wp_render_elements_support( $block_content, $block ) {
 	}
 	$link_color_declaration = esc_html( safecss_filter_attr( "color: $link_color" ) );
 
-	$style = "<style>.$class_name a{" . $link_color_declaration . ";}</style>\n";
+	$style = ".$class_name a{" . $link_color_declaration . ';}';
 
 	// Like the layout hook this assumes the hook only applies to blocks with a single wrapper.
 	// Retrieve the opening tag of the first HTML element.
@@ -68,17 +68,7 @@ function wp_render_elements_support( $block_content, $block ) {
 		$content              = substr_replace( $block_content, ' class="' . $class_name . '"', $first_element_offset + strlen( $first_element ) - 1, 0 );
 	}
 
-	/*
-	 * Ideally styles should be loaded in the head, but blocks may be parsed
-	 * after that, so loading in the footer for now.
-	 * See https://core.trac.wordpress.org/ticket/53494.
-	 */
-	add_action(
-		'wp_footer',
-		static function () use ( $style ) {
-			echo $style;
-		}
-	);
+	wp_enqueue_block_support( $style );
 
 	return $content;
 }
diff --git a/src/wp-includes/block-supports/layout.php b/src/wp-includes/block-supports/layout.php
index 529a775a92..e225a637ce 100644
--- a/src/wp-includes/block-supports/layout.php
+++ b/src/wp-includes/block-supports/layout.php
@@ -175,17 +175,7 @@ function wp_render_layout_support_flag( $block_content, $block ) {
 		1
 	);
 
-	/*
-	 * Ideally styles should be loaded in the head, but blocks may be parsed
-	 * after that, so loading in the footer for now.
-	 * See https://core.trac.wordpress.org/ticket/53494.
-	 */
-	add_action(
-		'wp_footer',
-		static function () use ( $style ) {
-			echo '<style>' . $style . '</style>';
-		}
-	);
+	wp_enqueue_block_support( $style );
 
 	return $content;
 }
diff --git a/src/wp-includes/blocks.php b/src/wp-includes/blocks.php
index cec2f36925..ae1fc9bffe 100644
--- a/src/wp-includes/blocks.php
+++ b/src/wp-includes/blocks.php
@@ -1332,3 +1332,29 @@ function _wp_multiple_block_styles( $metadata ) {
 	return $metadata;
 }
 add_filter( 'block_type_metadata', '_wp_multiple_block_styles' );
+
+/**
+ * This function takes care of adding inline styles
+ * in the proper place, depending on the theme in use.
+ *
+ * For block themes, it's loaded in the head.
+ * For classic ones, it's loaded in the body
+ * because the wp_head action (and wp_enqueue_scripts)
+ * happens before the render_block.
+ *
+ * See https://core.trac.wordpress.org/ticket/53494.
+ *
+ * @param string $style String containing the CSS styles to be added.
+ */
+function wp_enqueue_block_support( $style ) {
+	$action_hook_name = 'wp_footer';
+	if ( wp_is_block_theme() ) {
+		$action_hook_name = 'wp_enqueue_scripts';
+	}
+	add_action(
+		$action_hook_name,
+		function () use ( $style ) {
+			echo "<style>$style</style>\n";
+		}
+	);
+}