Fix export async function failure: 'SyntaxError: Cannot use keyword 'await' outside an async function'

src/parsing/preserve-named-constant-export.ts

@@ -14,12 +14,7 @@
  * limitations under the License.
  */
 
-import {
-  ExpressionStatement,
-  AssignmentExpression,
-  FunctionExpression,
-  MemberExpression,
-} from 'estree';
+import { ExpressionStatement, AssignmentExpression, FunctionExpression, MemberExpression } from 'estree';
 import { ExportDetails, Range } from '../types';
 import MagicString from 'magic-string';
 
@@ -37,21 +32,21 @@ function PreserveFunction(
   const functionExpression = assignmentExpression.right as FunctionExpression;
   const [memberExpressionObjectStart] = memberExpression.object.range as Range;
   const functionName = exportInline ? exportDetails.exported : exportDetails.local;
-
+  const functionAsync = functionExpression.async;
   if (functionExpression.params.length > 0) {
     const [paramsStart] = functionExpression.params[0].range as Range;
     // FunctionExpression has parameters.
     source.overwrite(
       memberExpressionObjectStart,
       paramsStart,
-      `${exportInline ? 'export ' : ''}function ${functionName}(`,
+      `${exportInline ? 'export ' : ''}${functionAsync ? 'async ' : ''}function ${functionName}(`,
     );
   } else {
     const [bodyStart] = functionExpression.body.range as Range;
     source.overwrite(
       memberExpressionObjectStart,
       bodyStart,
-      `${exportInline ? 'export ' : ''}function ${functionName}()`,
+      `${exportInline ? 'export ' : ''}${functionAsync ? 'async ' : ''}function ${functionName}()`,
     );
   }
 
@@ -74,21 +69,16 @@ function PreserveIdentifier(
 
   if (exportInline) {
     const output =
-      (exportDetails.exported === 'default'
-        ? `export default `
-        : `export var ${exportDetails.exported}=`) + `${code.substring(rightStart, rightEnd)};`;
+      (exportDetails.exported === 'default' ? `export default ` : `export var ${exportDetails.exported}=`) +
+      `${code.substring(rightStart, rightEnd)};`;
     source.overwrite(ancestorStart, ancestorEnd, output);
   } else if (exportDetails.source === null && 'name' in right) {
     // This is a locally defined identifier with a name we can use.
     exportDetails.local = right.name;
     source.remove(leftStart, ancestorEnd);
     return true;
   } else {
-    source.overwrite(
-      ancestorStart,
-      ancestorEnd,
-      `var ${exportDetails.local}=${code.substring(rightStart, rightEnd)};`,
-    );
+    source.overwrite(ancestorStart, ancestorEnd, `var ${exportDetails.local}=${code.substring(rightStart, rightEnd)};`);
   }
 
   return !exportInline;

test/export-default/async-function.test.js

@@ -0,0 +1,3 @@
+import { generator } from '../generator';
+
+generator('export-default', 'async-function', false, ['esm'], { stable: {} });

test/export-default/fixtures/async-function.js

@@ -0,0 +1,9 @@
+export async function asyncTest() {
+    await Promise.resolve('async-test');
+    console.log('async-test')
+}
+
+export async function asyncTestWithArgument(argument) {
+    await Promise.resolve('async-test-with-argument');
+    console.log(argument)
+}