throw error for recursive layout (#4730)

* throw error for recursive layout

* Create ten-apricots-admire.md

Co-authored-by: Rich Harris <[email protected]>

.changeset/ten-apricots-admire.md

@@ -0,0 +1,5 @@
+---
+"@sveltejs/kit": patch
+---
+
+throw error on encountering infinite layout loop

packages/kit/src/core/sync/create_manifest_data/index.js

@@ -312,6 +312,10 @@ function trace(file, path, tree, extensions) {
 		const node = tree.get(parts.join('/'));
 		const layout = node?.layouts[layout_id];
 
+		if (layout?.file && layouts.indexOf(layout.file) > -1) {
+			throw new Error(`Recursive layout detected: ${layout.file} -> ${layouts.join(' -> ')}`);
+		}
+
 		// any segment that has neither a __layout nor an __error can be discarded.
 		// in other words these...
 		//  layouts: [a, , b, c]

packages/kit/src/core/sync/create_manifest_data/index.spec.js

@@ -551,6 +551,22 @@ test('errors on duplicate layout definition', () => {
 	);
 });
 
+test.only('errors on recursive name layout', () => {
+	assert.throws(
+		() => create('samples/named-layout-recursive-1'),
+		/Recursive layout detected: samples\/named-layout-recursive-1\/__layout-a@b\.svelte -> samples\/named-layout-recursive-1\/__layout-b@a\.svelte -> samples\/named-layout-recursive-1\/__layout-a@b\.svelte/
+	);
+	assert.throws(
+		() => create('samples/named-layout-recursive-2'),
+		/Recursive layout detected: samples\/named-layout-recursive-2\/__layout-a@a\.svelte -> samples\/named-layout-recursive-2\/__layout-a@a\.svelte/
+	);
+
+	assert.throws(
+		() => create('samples/named-layout-recursive-3'),
+		/Recursive layout detected: samples\/named-layout-recursive-3\/__layout@a\.svelte -> samples\/named-layout-recursive-3\/__layout-a@default\.svelte -> samples\/named-layout-recursive-3\/__layout@a\.svelte/
+	);
+});
+
 test('allows for __tests__ directories', () => {
 	const { routes } = create('samples/legal-dunder');