From 4a9c4c6f50c013466f5f37595f2c9c87ea701358 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 23 Jan 2025 09:10:23 -0500
Subject: [PATCH] use proper compiler error for await-in-legacy-mode

---
 .../98-reference/.generated/compile-errors.md |  6 ++++
 .../98-reference/.generated/shared-errors.md  |  2 ++
 .../svelte/messages/compile-errors/script.md  |  4 +++
 packages/svelte/src/compiler/errors.js        |  9 ++++++
 .../2-analyze/visitors/AwaitExpression.js     |  3 +-
 packages/svelte/src/internal/shared/errors.js | 30 +++++++++----------
 6 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/documentation/docs/98-reference/.generated/compile-errors.md b/documentation/docs/98-reference/.generated/compile-errors.md
index 2fef3bd45d..f83c1b47f4 100644
--- a/documentation/docs/98-reference/.generated/compile-errors.md
+++ b/documentation/docs/98-reference/.generated/compile-errors.md
@@ -498,6 +498,12 @@ The arguments keyword cannot be used within the template or at the top level of
 %message%
 ```
 
+### legacy_await_invalid
+
+```
+Cannot use `await` at the top level of a component, or in the template, unless in runes mode
+```
+
 ### legacy_export_invalid
 
 ```
diff --git a/documentation/docs/98-reference/.generated/shared-errors.md b/documentation/docs/98-reference/.generated/shared-errors.md
index df49facef7..084d6c140b 100644
--- a/documentation/docs/98-reference/.generated/shared-errors.md
+++ b/documentation/docs/98-reference/.generated/shared-errors.md
@@ -6,6 +6,8 @@
 Cannot await outside a `<svelte:boundary>` with a `pending` snippet
 ```
 
+TODO
+
 ### invalid_default_snippet
 
 ```
diff --git a/packages/svelte/messages/compile-errors/script.md b/packages/svelte/messages/compile-errors/script.md
index 0aa6fbed90..3f0dc21d13 100644
--- a/packages/svelte/messages/compile-errors/script.md
+++ b/packages/svelte/messages/compile-errors/script.md
@@ -98,6 +98,10 @@ This turned out to be buggy and unpredictable, particularly when working with de
 
 > The arguments keyword cannot be used within the template or at the top level of a component
 
+## legacy_await_invalid
+
+> Cannot use `await` at the top level of a component, or in the template, unless in runes mode
+
 ## legacy_export_invalid
 
 > Cannot use `export let` in runes mode — use `$props()` instead
diff --git a/packages/svelte/src/compiler/errors.js b/packages/svelte/src/compiler/errors.js
index 53a6ac6849..a5ce88d62d 100644
--- a/packages/svelte/src/compiler/errors.js
+++ b/packages/svelte/src/compiler/errors.js
@@ -497,6 +497,15 @@ export function typescript_invalid_feature(node, feature) {
 	e(node, 'typescript_invalid_feature', `TypeScript language features like ${feature} are not natively supported, and their use is generally discouraged. Outside of \`<script>\` tags, these features are not supported. For use within \`<script>\` tags, you will need to use a preprocessor to convert it to JavaScript before it gets passed to the Svelte compiler. If you are using \`vitePreprocess\`, make sure to specifically enable preprocessing script tags (\`vitePreprocess({ script: true })\`)\nhttps://svelte.dev/e/typescript_invalid_feature`);
 }
 
+/**
+ * Cannot use `await` at the top level of a component, or in the template, unless in runes mode
+ * @param {null | number | NodeLike} node
+ * @returns {never}
+ */
+export function legacy_await_invalid(node) {
+	e(node, 'legacy_await_invalid', `Cannot use \`await\` at the top level of a component, or in the template, unless in runes mode\nhttps://svelte.dev/e/legacy_await_invalid`);
+}
+
 /**
  * Declaration cannot be empty
  * @param {null | number | NodeLike} node
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
index cf1665a02c..5b2005fbe4 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
@@ -1,5 +1,6 @@
 /** @import { AwaitExpression } from 'estree' */
 /** @import { Context } from '../types' */
+import * as e from '../../../errors.js';
 
 /**
  * @param {AwaitExpression} node
@@ -32,7 +33,7 @@ export function AwaitExpression(node, context) {
 
 	if (suspend) {
 		if (!context.state.analysis.runes) {
-			throw new Error('TODO runes mode only');
+			e.legacy_await_invalid(node);
 		}
 
 		context.state.analysis.suspenders.set(node, preserve_context);
diff --git a/packages/svelte/src/internal/shared/errors.js b/packages/svelte/src/internal/shared/errors.js
index c709c431ef..2062c9782a 100644
--- a/packages/svelte/src/internal/shared/errors.js
+++ b/packages/svelte/src/internal/shared/errors.js
@@ -2,6 +2,21 @@
 
 import { DEV } from 'esm-env';
 
+/**
+ * Cannot await outside a `<svelte:boundary>` with a `pending` snippet
+ * @returns {never}
+ */
+export function await_outside_boundary() {
+	if (DEV) {
+		const error = new Error(`await_outside_boundary\nCannot await outside a \`<svelte:boundary>\` with a \`pending\` snippet\nhttps://svelte.dev/e/await_outside_boundary`);
+
+		error.name = 'Svelte error';
+		throw error;
+	} else {
+		throw new Error(`https://svelte.dev/e/await_outside_boundary`);
+	}
+}
+
 /**
  * Cannot use `{@render children(...)}` if the parent component uses `let:` directives. Consider using a named snippet instead
  * @returns {never}
@@ -62,19 +77,4 @@ export function svelte_element_invalid_this_value() {
 	} else {
 		throw new Error(`https://svelte.dev/e/svelte_element_invalid_this_value`);
 	}
-}
-
-/**
- * Cannot await outside a `<svelte:boundary>` with a `pending` snippet
- * @returns {never}
- */
-export function await_outside_boundary() {
-	if (DEV) {
-		const error = new Error(`await_outside_boundary\nCannot await outside a \`<svelte:boundary>\` with a \`pending\` snippet\nhttps://svelte.dev/e/await_outside_boundary`);
-
-		error.name = 'Svelte error';
-		throw error;
-	} else {
-		throw new Error(`https://svelte.dev/e/await_outside_boundary`);
-	}
 }
\ No newline at end of file