fix: support using keyword

Author: Rich-Harris

.changeset/dull-cheetahs-watch.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: support `using` keyword

packages/svelte/package.json

@@ -164,9 +164,9 @@
   "dependencies": {
     "@ampproject/remapping": "^2.3.0",
     "@jridgewell/sourcemap-codec": "^1.5.0",
-    "@types/estree": "^1.0.5",
-    "acorn": "^8.12.1",
     "@sveltejs/acorn-typescript": "^1.0.5",
+    "@types/estree": "^1.0.5",
+    "acorn": "^8.15.0",
     "aria-query": "^5.3.1",
     "axobject-query": "^4.1.0",
     "clsx": "^2.1.1",

packages/svelte/src/compiler/phases/1-parse/acorn.js

@@ -36,7 +36,7 @@ export function parse(source, typescript, is_script) {
 		ast = parser.parse(source, {
 			onComment,
 			sourceType: 'module',
-			ecmaVersion: 16,
+			ecmaVersion: 'latest',
 			locations: true
 		});
 	} finally {
@@ -64,7 +64,7 @@ export function parse_expression_at(source, typescript, index) {
 	const ast = parser.parseExpressionAt(source, index, {
 		onComment,
 		sourceType: 'module',
-		ecmaVersion: 16,
+		ecmaVersion: 'latest',
 		locations: true
 	});
 

packages/svelte/test.js

@@ -0,0 +1,12 @@
+import { parse } from 'acorn';
+
+const code = `
+using bar = baz();
+`;
+
+const ast = parse(code, {
+	sourceType: 'module',
+	ecmaVersion: 'latest'
+});
+
+console.log(JSON.stringify(ast, null, '  '));