Template Part: Prevent infinite recursion

Based on #28405 from @mcsf. Tries to apply the same technique used for Reusable block to prevent infinite recursion when the same block is inserted into itself at any level of nesting.
WordPress · Mar 3, 2021 · ceec567 · ceec567
1 parent f16ab0e
commit ceec567
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Showing 2 changed files with 45 additions and 4 deletions.
diff --git a/packages/block-library/src/template-part/edit/index.js b/packages/block-library/src/template-part/edit/index.js
@@ -5,6 +5,7 @@ import { useSelect } from '@wordpress/data';
 import {
 	BlockControls,
 	useBlockProps,
+	__experimentalUseNoRecursiveRenders as useNoRecursiveRenders,
 	Warning,
 	store as blockEditorStore,
 } from '@wordpress/block-editor';
@@ -34,6 +35,10 @@ export default function TemplatePartEdit( {
 } ) {
 	const templatePartId = theme && slug ? theme + '//' + slug : null;
 
+	const [ hasAlreadyRendered, RecursionProvider ] = useNoRecursiveRenders(
+		templatePartId
+	);
+
 	// Set the postId block attribute if it did not exist,
 	// but wait until the inner blocks have loaded to allow
 	// new edits to trigger this.
@@ -70,8 +75,7 @@ export default function TemplatePartEdit( {
 	);
 
 	const blockProps = useBlockProps();
-	const isPlaceholder = ! slug;
-	const isEntityAvailable = ! isPlaceholder && ! isMissing;
+	const isEntityAvailable = slug && ! isMissing;
 	const TagName = tagName || getTagBasedOnArea( area );
 
 	// We don't want to render a missing state if we have any inner blocks.
@@ -91,8 +95,18 @@ export default function TemplatePartEdit( {
 		);
 	}
 
+	if ( hasAlreadyRendered ) {
+		return (
+			<TagName { ...blockProps }>
+				<Warning>
+					{ __( 'Block cannot be rendered inside itself.' ) }
+				</Warning>
+			</TagName>
+		);
+	}
+
 	return (
-		<>
+		<RecursionProvider>
 			<TemplatePartAdvancedControls
 				tagName={ tagName }
 				setAttributes={ setAttributes }
@@ -144,6 +158,6 @@ export default function TemplatePartEdit( {
 				) }
 				{ ! isPlaceholder && ! isResolved && <Spinner /> }
 			</TagName>
-		</>
+		</RecursionProvider>
 	);
 }
diff --git a/packages/block-library/src/template-part/index.php b/packages/block-library/src/template-part/index.php
@@ -13,6 +13,8 @@
  * @return string The render.
  */
 function render_block_core_template_part( $attributes ) {
+	static $seen_content = array();
+
 	$content = null;
 	$area    = WP_TEMPLATE_PART_AREA_UNCATEGORIZED;
 
@@ -60,6 +62,31 @@ function render_block_core_template_part( $attributes ) {
 		return 'Template Part Not Found';
 	}
 
+	if ( in_array( $content, $seen_content, true ) ) {
+		if ( ! is_admin() ) {
+			trigger_error(
+				sprintf(
+					// translators: %s is the user-provided title of the reusable block.
+					__( 'Could not render Template Part with the slug <strong>%s</strong>: blocks cannot be rendered inside themselves.' ),
+					$attributes['slug']
+				),
+				E_USER_WARNING
+			);
+		}
+
+		// WP_DEBUG_DISPLAY must only be honored when WP_DEBUG. This precedent
+		// is set in `wp_debug_mode()`.
+		$is_debug = defined( 'WP_DEBUG' ) && WP_DEBUG &&
+			defined( 'WP_DEBUG_DISPLAY' ) && WP_DEBUG_DISPLAY;
+
+		return $is_debug ?
+			// translators: Visible only in the front end, this warning takes the place of a faulty block.
+			__( '[block rendering halted]' ) :
+			'';
+	}
+
+	$seen_content[] = $content;
+
 	// Run through the actions that are typically taken on the_content.
 	$content = do_blocks( $content );
 	$content = wptexturize( $content );