From 3c3a542c058b2b1e68e57e77f5255bca6842c793 Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Wed, 17 Jul 2024 14:06:24 +0200
Subject: [PATCH] fix: error on snippet rest parameters (#12472)

closes #12464
---
 packages/svelte/messages/compile-errors/template.md      | 2 +-
 packages/svelte/src/compiler/errors.js                   | 4 ++--
 .../svelte/src/compiler/phases/2-analyze/validation.js   | 6 ++++++
 .../compiler-errors/samples/snippet-rest-args/_config.js | 9 +++++++++
 .../samples/snippet-rest-args/main.svelte                | 3 +++
 5 files changed, 21 insertions(+), 3 deletions(-)
 create mode 100644 packages/svelte/tests/compiler-errors/samples/snippet-rest-args/_config.js
 create mode 100644 packages/svelte/tests/compiler-errors/samples/snippet-rest-args/main.svelte

diff --git a/packages/svelte/messages/compile-errors/template.md b/packages/svelte/messages/compile-errors/template.md
index 517e5e730f..9b43e99820 100644
--- a/packages/svelte/messages/compile-errors/template.md
+++ b/packages/svelte/messages/compile-errors/template.md
@@ -250,7 +250,7 @@
 
 ## snippet_invalid_rest_parameter
 
-> snippets do not support rest parameters; use an array instead
+> Snippets do not support rest parameters; use an array instead
 
 ## snippet_shadowing_prop
 
diff --git a/packages/svelte/src/compiler/errors.js b/packages/svelte/src/compiler/errors.js
index b092e262db..b4dcad4e4c 100644
--- a/packages/svelte/src/compiler/errors.js
+++ b/packages/svelte/src/compiler/errors.js
@@ -1108,12 +1108,12 @@ export function snippet_conflict(node) {
 }
 
 /**
- * snippets do not support rest parameters; use an array instead
+ * Snippets do not support rest parameters; use an array instead
  * @param {null | number | NodeLike} node
  * @returns {never}
  */
 export function snippet_invalid_rest_parameter(node) {
-	e(node, "snippet_invalid_rest_parameter", "snippets do not support rest parameters; use an array instead");
+	e(node, "snippet_invalid_rest_parameter", "Snippets do not support rest parameters; use an array instead");
 }
 
 /**
diff --git a/packages/svelte/src/compiler/phases/2-analyze/validation.js b/packages/svelte/src/compiler/phases/2-analyze/validation.js
index fcbb227a71..a5b22c666f 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/validation.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/validation.js
@@ -674,6 +674,12 @@ const validation = {
 	SnippetBlock(node, context) {
 		validate_block_not_empty(node.body, context);
 
+		for (const arg of node.parameters) {
+			if (arg.type === 'RestElement') {
+				e.snippet_invalid_rest_parameter(arg);
+			}
+		}
+
 		context.next({ ...context.state, parent_element: null });
 
 		const { path } = context;
diff --git a/packages/svelte/tests/compiler-errors/samples/snippet-rest-args/_config.js b/packages/svelte/tests/compiler-errors/samples/snippet-rest-args/_config.js
new file mode 100644
index 0000000000..f305520831
--- /dev/null
+++ b/packages/svelte/tests/compiler-errors/samples/snippet-rest-args/_config.js
@@ -0,0 +1,9 @@
+import { test } from '../../test';
+
+export default test({
+	error: {
+		code: 'snippet_invalid_rest_parameter',
+		message: 'Snippets do not support rest parameters; use an array instead',
+		position: [19, 26]
+	}
+});
diff --git a/packages/svelte/tests/compiler-errors/samples/snippet-rest-args/main.svelte b/packages/svelte/tests/compiler-errors/samples/snippet-rest-args/main.svelte
new file mode 100644
index 0000000000..f345bf1956
--- /dev/null
+++ b/packages/svelte/tests/compiler-errors/samples/snippet-rest-args/main.svelte
@@ -0,0 +1,3 @@
+{#snippet children(...args)}
+	{args}
+{/snippet}