Allow themes to add inline styles for all blocks when using lazy styl…

…es loading (#32275)

* register empty styles for blocks that don't have any

* add style & editorStyle in block.json where missing

* only do this if the file doesn't exist

* meh, missed the 2nd arg here

* Use a filter instead of modifying each block.json file.

* Use the register_block_type_args filter

* Move filter to compat files

lib/blocks.php

@@ -199,6 +199,8 @@ function gutenberg_register_core_block_styles( $block_name ) {
 
 		// Add a reference to the stylesheet's path to allow calculations for inlining styles in `wp_head`.
 		wp_style_add_data( "wp-block-{$block_name}", 'path', gutenberg_dir_path() . $style_path );
+	} else {
+		wp_register_style( "wp-block-{$block_name}", false );
 	}
 
 	if ( file_exists( gutenberg_dir_path() . $editor_style_path ) ) {
@@ -210,6 +212,8 @@ function gutenberg_register_core_block_styles( $block_name ) {
 			filemtime( gutenberg_dir_path() . $editor_style_path )
 		);
 		wp_style_add_data( "wp-block-{$block_name}-editor", 'rtl', 'replace' );
+	} else {
+		wp_register_style( "wp-block-{$block_name}-editor", false );
 	}
 }
 
@@ -466,5 +470,4 @@ function gutenberg_migrate_old_typography_shape( $metadata ) {
 	return $metadata;
 }
 
-
 add_filter( 'block_type_metadata', 'gutenberg_migrate_old_typography_shape' );

lib/compat/wordpress-5.8/block-editor.php

@@ -371,3 +371,27 @@ function gutenberg_block_editor_rest_api_preload( array $preload_paths, $block_e
 		'after'
 	);
 }
+
+/**
+ * Filters the arguments for registering a block type.
+ *
+ * @todo Remove from the Gutenberg plugin when WordPress 5.8 is the minimum required version.
+ *
+ * @param array $args Array of arguments for registering a block type.
+ *
+ * @return array Returns the $metadata with any missing `style` and `editorStyle` added.
+ */
+function gutenberg_add_missing_styles_to_core_block_json( $args ) {
+	if ( ! empty( $args['name'] ) && 0 === strpos( $args['name'], 'core/' ) ) {
+		$block_name = str_replace( 'core/', '', $args['name'] );
+
+		if ( ! isset( $args['style'] ) ) {
+			$args['style'] = "wp-block-$block_name";
+		}
+		if ( ! isset( $args['editor_style'] ) ) {
+			$args['editor_style'] = "wp-block-$block_name-editor";
+		}
+	}
+	return $args;
+}
+add_filter( 'register_block_type_args', 'gutenberg_add_missing_styles_to_core_block_json' );