Block Bindings: Communicate supported block attributes from server side

src/wp-includes/block-bindings.php

@@ -129,3 +129,56 @@ function get_all_registered_block_bindings_sources() {
 function get_block_bindings_source( string $source_name ) {
 	return WP_Block_Bindings_Registry::get_instance()->get_registered( $source_name );
 }
+
+/**
+ * Retrieves the list of block attributes supported by block bindings.
+ *
+ * @since 6.9.0
+ *
+ * @param string $block_type The block type whose supported attributes are being retrieved.
+ * @return array The list of block attributes that are supported by block bindings.
+ */
+function get_block_bindings_supported_attributes( $block_type ) {
+	$block_bindings_supported_attributes = array(
+		'core/paragraph' => array( 'content' ),
+		'core/heading'   => array( 'content' ),
+		'core/image'     => array( 'id', 'url', 'title', 'alt', 'caption' ),
+		'core/button'    => array( 'url', 'text', 'linkTarget', 'rel' ),
+		'core/post-date' => array( 'datetime' ),
+	);
+
+	$supported_block_attributes =
+		$block_bindings_supported_attributes[ $block_type ] ??
+		array();
+
+	/**
+	 * Filters the supported block attributes for block bindings.
+	 *
+	 * @since 6.9.0
+	 *
+	 * @param string[] $supported_block_attributes The block's attributes that are supported by block bindings.
+	 * @param string   $block_type                 The block type whose attributes are being filtered.
+	 */
+	$supported_block_attributes = apply_filters(
+		'block_bindings_supported_attributes',
+		$supported_block_attributes,
+		$block_type
+	);
+
+	/**
+	 * Filters the supported block attributes for block bindings.
+	 *
+	 * The dynamic portion of the hook name, `$block_type`, refers to the block type
+	 * whose attributes are being filtered.
+	 *
+	 * @since 6.9.0
+	 *
+	 * @param string[] $supported_block_attributes The block's attributes that are supported by block bindings.
+	 */
+	$supported_block_attributes = apply_filters(
+		"block_bindings_supported_attributes_{$block_type}",
+		$supported_block_attributes
+	);
+
+	return $supported_block_attributes;
+}

src/wp-includes/block-editor.php

@@ -496,6 +496,14 @@ function get_block_editor_settings( array $custom_settings, $block_editor_contex
 		$custom_settings
 	);
 
+	$editor_settings['__experimentalBlockBindingsSupportedAttributes'] = array();
+	foreach ( array_keys( WP_Block_Type_Registry::get_instance()->get_all_registered() ) as $block_type ) {
+		$supported_block_attributes = get_block_bindings_supported_attributes( $block_type );
+		if ( ! empty( $supported_block_attributes ) ) {
+			$editor_settings['__experimentalBlockBindingsSupportedAttributes'][ $block_type ] = $supported_block_attributes;
+		}
+	}
+
 	$global_styles = array();
 	$presets       = array(
 		array(

src/wp-includes/class-wp-block.php

@@ -98,22 +98,6 @@ class WP_Block {
 	 */
 	public $inner_content = array();
 
-	/**
-	 * List of supported block attributes for block bindings.
-	 *
-	 * @since 6.9.0
-	 * @var array
-	 *
-	 * @see WP_Block::process_block_bindings()
-	 */
-	private const BLOCK_BINDINGS_SUPPORTED_ATTRIBUTES = array(
-		'core/paragraph' => array( 'content' ),
-		'core/heading'   => array( 'content' ),
-		'core/image'     => array( 'id', 'url', 'title', 'alt', 'caption' ),
-		'core/button'    => array( 'url', 'text', 'linkTarget', 'rel' ),
-		'core/post-date' => array( 'datetime' ),
-	);
-
 	/**
 	 * Constructor.
 	 *
@@ -297,38 +281,7 @@ private function process_block_bindings() {
 		$block_type                 = $this->name;
 		$parsed_block               = $this->parsed_block;
 		$computed_attributes        = array();
-		$supported_block_attributes =
-			self::BLOCK_BINDINGS_SUPPORTED_ATTRIBUTES[ $block_type ] ??
-			array();
-
-		/**
-		 * Filters the supported block attributes for block bindings.
-		 *
-		 * @since 6.9.0
-		 *
-		 * @param string[] $supported_block_attributes The block's attributes that are supported by block bindings.
-		 * @param string   $block_type                 The block type whose attributes are being filtered.
-		 */
-		$supported_block_attributes = apply_filters(
-			'block_bindings_supported_attributes',
-			$supported_block_attributes,
-			$block_type
-		);
-
-		/**
-		 * Filters the supported block attributes for block bindings.
-		 *
-		 * The dynamic portion of the hook name, `$block_type`, refers to the block type
-		 * whose attributes are being filtered.
-		 *
-		 * @since 6.9.0
-		 *
-		 * @param string[] $supported_block_attributes The block's attributes that are supported by block bindings.
-		 */
-		$supported_block_attributes = apply_filters(
-			"block_bindings_supported_attributes_{$block_type}",
-			$supported_block_attributes
-		);
+		$supported_block_attributes = get_block_bindings_supported_attributes( $block_type );
 
 		// If the block doesn't have the bindings property, isn't one of the supported
 		// block types, or the bindings property is not an array, return the block content.