fix(parser): validate await context for await using declarations (#26495)

Reject `await using` in non-async functions and ordinary generators, including `for` and `for...of` loop heads. Treat top-level `await using` as module syntax when the source type is unambiguous.

crates/oxc_parser/src/js/declaration.rs

@@ -189,6 +189,16 @@ impl<'a, C: Config> ParserImpl<'a, C> {
 
         let is_await = self.eat(Kind::Await);
         let kind = if is_await {
+            if !self.ctx.has_await() {
+                let error = diagnostics::await_expression(Span::sized(start, 5));
+                if self.ctx.has_top_level() {
+                    // Top-level `await using` is module syntax in unambiguous mode.
+                    self.module_record_builder.set_module_syntax();
+                    self.error_on_script(error);
+                } else {
+                    self.error(error);
+                }
+            }
             VariableDeclarationKind::AwaitUsing
         } else {
             VariableDeclarationKind::Using

crates/oxc_semantic/tests/fixtures/oxc/js/declarations/using.snap

@@ -7,7 +7,7 @@ input_file: crates/oxc_semantic/tests/fixtures/oxc/js/declarations/using.js
     "children": [
       {
         "children": [],
-        "flags": "ScopeFlags(0x0)",
+        "flags": "ScopeFlags(StrictMode)",
         "id": 1,
         "node": "BlockStatement",
         "symbols": [
@@ -22,7 +22,7 @@ input_file: crates/oxc_semantic/tests/fixtures/oxc/js/declarations/using.js
       },
       {
         "children": [],
-        "flags": "ScopeFlags(0x0)",
+        "flags": "ScopeFlags(StrictMode)",
         "id": 2,
         "node": "BlockStatement",
         "symbols": [
@@ -37,7 +37,7 @@ input_file: crates/oxc_semantic/tests/fixtures/oxc/js/declarations/using.js
       },
       {
         "children": [],
-        "flags": "ScopeFlags(0x0)",
+        "flags": "ScopeFlags(StrictMode)",
         "id": 3,
         "node": "BlockStatement",
         "symbols": [
@@ -52,7 +52,7 @@ input_file: crates/oxc_semantic/tests/fixtures/oxc/js/declarations/using.js
       },
       {
         "children": [],
-        "flags": "ScopeFlags(0x0)",
+        "flags": "ScopeFlags(StrictMode)",
         "id": 4,
         "node": "BlockStatement",
         "symbols": [
@@ -69,13 +69,13 @@ input_file: crates/oxc_semantic/tests/fixtures/oxc/js/declarations/using.js
         "children": [
           {
             "children": [],
-            "flags": "ScopeFlags(0x0)",
+            "flags": "ScopeFlags(StrictMode)",
             "id": 6,
             "node": "BlockStatement",
             "symbols": []
           }
         ],
-        "flags": "ScopeFlags(0x0)",
+        "flags": "ScopeFlags(StrictMode)",
         "id": 5,
         "node": "ForOfStatement",
         "symbols": [
@@ -92,13 +92,13 @@ input_file: crates/oxc_semantic/tests/fixtures/oxc/js/declarations/using.js
         "children": [
           {
             "children": [],
-            "flags": "ScopeFlags(0x0)",
+            "flags": "ScopeFlags(StrictMode)",
             "id": 8,
             "node": "BlockStatement",
             "symbols": []
           }
         ],
-        "flags": "ScopeFlags(0x0)",
+        "flags": "ScopeFlags(StrictMode)",
         "id": 7,
         "node": "ForOfStatement",
         "symbols": [
@@ -112,7 +112,7 @@ input_file: crates/oxc_semantic/tests/fixtures/oxc/js/declarations/using.js
         ]
       }
     ],
-    "flags": "ScopeFlags(Top)",
+    "flags": "ScopeFlags(StrictMode | Top)",
     "id": 0,
     "node": "Program",
     "symbols": []

tasks/coverage/misc/fail/await-using-context.js

@@ -0,0 +1,11 @@
+function f() {
+  await using x = null;
+  for (await using y = null; ; ) {}
+  for (await using z of []) {}
+}
+
+function* g() {
+  await using x = null;
+  for (await using y = null; ; ) {}
+  for (await using z of []) {}
+}

tasks/coverage/misc/pass/await-using-unambiguous.js

@@ -0,0 +1 @@
+await using x = null;

tasks/coverage/snapshots/codegen_misc.snap

@@ -1,3 +1,3 @@
 codegen_misc Summary:
-AST Parsed     : 97/97 (100.00%)
-Positive Passed: 97/97 (100.00%)
+AST Parsed     : 98/98 (100.00%)
+Positive Passed: 98/98 (100.00%)

tasks/coverage/snapshots/formatter_misc.snap

@@ -1,3 +1,3 @@
 formatter_misc Summary:
-AST Parsed     : 97/97 (100.00%)
-Positive Passed: 97/97 (100.00%)
+AST Parsed     : 98/98 (100.00%)
+Positive Passed: 98/98 (100.00%)

tasks/coverage/snapshots/lexer_misc.snap

@@ -1,3 +1,3 @@
 lexer_misc Summary:
-AST Parsed     : 297/297 (100.00%)
-Positive Passed: 297/297 (100.00%)
+AST Parsed     : 299/299 (100.00%)
+Positive Passed: 299/299 (100.00%)

tasks/coverage/snapshots/parser_babel.snap

@@ -8823,6 +8823,15 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Wrap this declaration in a block statement
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:2:13]
+ 1 │ {
+ 2 │   while (1) await using a = foo;
+   ·             ─────
+ 3 │   for (;0;) await using b = foo;
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × Lexical declaration cannot appear in a single-statement context
    ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:2:13]
  1 │ {
@@ -8832,6 +8841,15 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Wrap this declaration in a block statement
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:3:13]
+ 2 │   while (1) await using a = foo;
+ 3 │   for (;0;) await using b = foo;
+   ·             ─────
+ 4 │   do await using c = foo; while (1);
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × Lexical declaration cannot appear in a single-statement context
    ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:3:13]
  2 │   while (1) await using a = foo;
@@ -8841,6 +8859,15 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Wrap this declaration in a block statement
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:4:6]
+ 3 │   for (;0;) await using b = foo;
+ 4 │   do await using c = foo; while (1);
+   ·      ─────
+ 5 │   if (1) await using d = foo;
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × Lexical declaration cannot appear in a single-statement context
    ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:4:6]
  3 │   for (;0;) await using b = foo;
@@ -8850,6 +8877,15 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Wrap this declaration in a block statement
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:5:10]
+ 4 │   do await using c = foo; while (1);
+ 5 │   if (1) await using d = foo;
+   ·          ─────
+ 6 │   with (1) await using e = foo;
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × Lexical declaration cannot appear in a single-statement context
    ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:5:10]
  4 │   do await using c = foo; while (1);
@@ -8859,6 +8895,15 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Wrap this declaration in a block statement
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:6:12]
+ 5 │   if (1) await using d = foo;
+ 6 │   with (1) await using e = foo;
+   ·            ─────
+ 7 │   label: await using f = foo;
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × Lexical declaration cannot appear in a single-statement context
    ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:6:12]
  5 │   if (1) await using d = foo;
@@ -8868,6 +8913,15 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Wrap this declaration in a block statement
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:7:10]
+ 6 │   with (1) await using e = foo;
+ 7 │   label: await using f = foo;
+   ·          ─────
+ 8 │ }
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × Lexical declaration cannot appear in a single-statement context
    ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-in-single-statement-context-sync/input.js:7:10]
  6 │   with (1) await using e = foo;
@@ -8913,6 +8967,13 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Wrap this declaration in a block statement
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-script-top-level-labeled-using-binding/input.js:1:8]
+ 1 │ label: await using x = bar();
+   ·        ─────
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × Lexical declaration cannot appear in a single-statement context
    ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-script-top-level-labeled-using-binding/input.js:1:8]
  1 │ label: await using x = bar();
@@ -8927,6 +8988,13 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Wrap this code in a block or use a module
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-script-top-level-using-binding/input.js:1:1]
+ 1 │ await using x = bar();
+   · ─────
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × 'using' declarations are not allowed at the top level of a script
    ╭─[babel/packages/babel-parser/test/fixtures/es2026/async-explicit-resource-management/invalid-script-top-level-using-binding/input.js:1:1]
  1 │ await using x = bar();
@@ -13786,6 +13854,15 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Try inserting a semicolon here
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:2:3]
+ 1 │ declare namespace invalid_namespace_var {
+ 2 │   await using A;
+   ·   ─────
+ 3 │   await using A1 = 0;
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × TS(1546): 'await using' declarations are not allowed in ambient contexts.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:2:15]
  1 │ declare namespace invalid_namespace_var {
@@ -13794,6 +13871,15 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
  3 │   await using A1 = 0;
    ╰────
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:3:3]
+ 2 │   await using A;
+ 3 │   await using A1 = 0;
+   ·   ─────
+ 4 │   await using A2: number = 0;
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × TS(1546): 'await using' declarations are not allowed in ambient contexts.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:3:15]
  2 │   await using A;
@@ -13802,6 +13888,15 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
  4 │   await using A2: number = 0;
    ╰────
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:4:3]
+ 3 │   await using A1 = 0;
+ 4 │   await using A2: number = 0;
+   ·   ─────
+ 5 │   await using B, C;
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × TS(1546): 'await using' declarations are not allowed in ambient contexts.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:4:15]
  3 │   await using A1 = 0;
@@ -13810,6 +13905,15 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
  5 │   await using B, C;
    ╰────
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:5:3]
+ 4 │   await using A2: number = 0;
+ 5 │   await using B, C;
+   ·   ─────
+ 6 │ }
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × TS(1546): 'await using' declarations are not allowed in ambient contexts.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/declare/invalid-namespace-await-using/input.ts:5:15]
  4 │   await using A2: number = 0;

tasks/coverage/snapshots/parser_misc.snap

@@ -1,7 +1,7 @@
 parser_misc Summary:
-AST Parsed     : 97/97 (100.00%)
-Positive Passed: 97/97 (100.00%)
-Negative Passed: 200/200 (100.00%)
+AST Parsed     : 98/98 (100.00%)
+Positive Passed: 98/98 (100.00%)
+Negative Passed: 201/201 (100.00%)
 
   × Cannot assign to 'arguments' in strict mode
    ╭─[misc/fail/arguments-eval-ambient.ts:2:13]
@@ -228,6 +228,60 @@ Negative Passed: 200/200 (100.00%)
  5 │     }
    ╰────
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[misc/fail/await-using-context.js:2:3]
+ 1 │ function f() {
+ 2 │   await using x = null;
+   ·   ─────
+ 3 │   for (await using y = null; ; ) {}
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[misc/fail/await-using-context.js:3:8]
+ 2 │   await using x = null;
+ 3 │   for (await using y = null; ; ) {}
+   ·        ─────
+ 4 │   for (await using z of []) {}
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[misc/fail/await-using-context.js:4:8]
+ 3 │   for (await using y = null; ; ) {}
+ 4 │   for (await using z of []) {}
+   ·        ─────
+ 5 │ }
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[misc/fail/await-using-context.js:8:3]
+ 7 │ function* g() {
+ 8 │   await using x = null;
+   ·   ─────
+ 9 │   for (await using y = null; ; ) {}
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
+  × `await` is only allowed within async functions and at the top levels of modules
+    ╭─[misc/fail/await-using-context.js:9:8]
+  8 │   await using x = null;
+  9 │   for (await using y = null; ; ) {}
+    ·        ─────
+ 10 │   for (await using z of []) {}
+    ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
+  × `await` is only allowed within async functions and at the top levels of modules
+    ╭─[misc/fail/await-using-context.js:10:8]
+  9 │   for (await using y = null; ; ) {}
+ 10 │   for (await using z of []) {}
+    ·        ─────
+ 11 │ }
+    ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × Expected `;` but found `,`
    ╭─[misc/fail/class-field-comma-expression.js:1:16]
  1 │ class C { x = a,b }

tasks/coverage/snapshots/parser_test262.snap

@@ -27711,6 +27711,14 @@ Negative Passed: 4651/4651 (100.00%)
     ╰────
   help: Wrap this declaration in a block statement
 
+  × `await` is only allowed within async functions and at the top levels of modules
+    ╭─[test262/test/language/statements/await-using/syntax/await-using-not-allowed-at-top-level-of-script.js:23:1]
+ 22 │ $DONOTEVALUATE();
+ 23 │ await using x = null;
+    · ─────
+    ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × 'using' declarations are not allowed at the top level of a script
     ╭─[test262/test/language/statements/await-using/syntax/await-using-not-allowed-at-top-level-of-script.js:23:1]
  22 │ $DONOTEVALUATE();

tasks/coverage/snapshots/parser_typescript.snap

@@ -28729,13 +28729,14 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/wit
    ╰────
   help: Remove the `export` here and add `export { x }` as a separate statement to export the declaration
 
-  × 'using' declarations are not allowed at the top level of a script
-   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.13.ts:1:1]
- 1 │ await using x = null;
-   · ─────────────────────
- 2 │ 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.13.ts:4:5]
+ 3 │ function f() {
+ 4 │     await using x = null;
+   ·     ─────
+ 5 │ }
    ╰────
-  help: Wrap this code in a block or use a module
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
 
   × Cannot use 'await using' in class static initialization block
    ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.14.ts:3:9]
@@ -28753,6 +28754,15 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/wit
  6 │         }
    ╰────
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:2:5]
+ 1 │ declare namespace N {
+ 2 │     await using x: { [Symbol.asyncDispose](): Promise<void> };
+   ·     ─────
+ 3 │     await using y: null;
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × TS(1546): 'await using' declarations are not allowed in ambient contexts.
    ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:2:17]
  1 │ declare namespace N {
@@ -28761,6 +28771,15 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/wit
  3 │     await using y: null;
    ╰────
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:3:5]
+ 2 │     await using x: { [Symbol.asyncDispose](): Promise<void> };
+ 3 │     await using y: null;
+   ·     ─────
+ 4 │ }
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × TS(1546): 'await using' declarations are not allowed in ambient contexts.
    ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:3:17]
  2 │     await using x: { [Symbol.asyncDispose](): Promise<void> };
@@ -28769,6 +28788,15 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/wit
  4 │ }
    ╰────
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:6:5]
+ 5 │ declare module 'M' {
+ 6 │     await using x: { [Symbol.asyncDispose](): Promise<void> };
+   ·     ─────
+ 7 │     await using y: null;
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × TS(1546): 'await using' declarations are not allowed in ambient contexts.
    ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:6:17]
  5 │ declare module 'M' {
@@ -28777,6 +28805,15 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/wit
  7 │     await using y: null;
    ╰────
 
+  × `await` is only allowed within async functions and at the top levels of modules
+   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:7:5]
+ 6 │     await using x: { [Symbol.asyncDispose](): Promise<void> };
+ 7 │     await using y: null;
+   ·     ─────
+ 8 │ }
+   ╰────
+  help: Either remove this `await` or add the `async` keyword to the enclosing function
+
   × TS(1546): 'await using' declarations are not allowed in ambient contexts.
    ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarations.16.ts:7:17]
  6 │     await using x: { [Symbol.asyncDispose](): Promise<void> };
@@ -28882,15 +28919,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/types/wit
  6 │ 
    ╰────
 
-  × `for await` loops are only allowed within async functions and at the top levels of modules
-   ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarationsInForAwaitOf.3.ts:5:5]
- 4 │ 
- 5 │ for await (await using of x);
-   ·     ─────
- 6 │ 
-   ╰────
-  help: Either remove this `await` or add the `async` keyword to the enclosing function
-
   × The left-hand side of a for...in statement cannot be an await using declaration.
    ╭─[typescript/tests/cases/conformance/statements/VariableStatements/usingDeclarations/awaitUsingDeclarationsInForIn.ts:2:10]
  1 │ async function main() {

tasks/coverage/snapshots/semantic_misc.snap

@@ -1,6 +1,6 @@
 semantic_misc Summary:
-AST Parsed     : 97/97 (100.00%)
-Positive Passed: 93/97 (95.88%)
+AST Parsed     : 98/98 (100.00%)
+Positive Passed: 94/98 (95.92%)
 semantic Error: tasks/coverage/misc/pass/declare-let-private.ts
 Bindings mismatch:
 after transform: ScopeId(0): ["private"]

tasks/coverage/snapshots/transformer_misc.snap

@@ -1,3 +1,3 @@
 transformer_misc Summary:
-AST Parsed     : 97/97 (100.00%)
-Positive Passed: 97/97 (100.00%)
+AST Parsed     : 98/98 (100.00%)
+Positive Passed: 98/98 (100.00%)

tasks/transform_conformance/src/test_case.rs

@@ -89,8 +89,11 @@ impl TestCase {
     fn source_type(path: &Path, options: &BabelOptions) -> SourceType {
         // Some babel test cases have a js extension, but contain typescript code.
         // Therefore, if the typescript plugin exists, enable typescript.
-        let mut source_type =
-            SourceType::from_path(path).unwrap().with_script(true).with_jsx(options.is_jsx());
+        let mut source_type = SourceType::from_path(path).unwrap().with_jsx(options.is_jsx());
+        // Preserve explicit module extensions; other fixtures default to scripts.
+        if !source_type.is_module() {
+            source_type = source_type.with_script(true);
+        }
         source_type = match options.source_type.as_deref() {
             Some("unambiguous") => source_type.with_unambiguous(true),
             Some("script") => source_type.with_script(true),