add @danez's changes

.eslintignore

@@ -6,6 +6,7 @@ packages/*/node_modules
 packages/*/lib
 packages/*/dist
 packages/*/test/fixtures
+packages/*/test/tmp
 vendor
 _babel.github.io
 Gulpfile.js

packages/babel-helper-remap-async-to-generator/src/index.js

@@ -146,6 +146,23 @@ function plainFunction(path: NodePath, callId: Object) {
     ]);
     declar._blockHoist = true;
 
+    if (path.parentPath.isExportDefaultDeclaration()) {
+      // change the path type so that replaceWith() does not wrap
+      // the identifier into an expressionStatement
+      path.parentPath.insertBefore(declar);
+      path.parentPath.replaceWith(
+        t.exportNamedDeclaration(null,
+          [
+            t.exportSpecifier(
+              t.identifier(asyncFnId.name),
+              t.identifier("default")
+            )
+          ]
+        )
+      );
+      return;
+    }
+
     path.replaceWith(declar);
   } else {
     const retFunction = container.body.body[1].argument;

packages/babel-plugin-transform-async-to-generator/test/fixtures/export-async/default-arrow-export/actual.js

@@ -0,0 +1 @@
+export default async () => { return await foo(); }

packages/babel-plugin-transform-async-to-generator/test/fixtures/export-async/default-arrow-export/expected.js

@@ -0,0 +1,8 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = babelHelpers.asyncToGenerator(function* () {
+  return yield foo();
+});

packages/babel-plugin-transform-async-to-generator/test/fixtures/export-async/default-export/actual.js

@@ -0,0 +1 @@
+export default async function myFunc() {}

packages/babel-plugin-transform-async-to-generator/test/fixtures/export-async/default-export/expected.js

@@ -0,0 +1,15 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+
+let myFunc = (() => {
+  var _ref = babelHelpers.asyncToGenerator(function* () {});
+
+  return function myFunc() {
+    return _ref.apply(this, arguments);
+  };
+})();
+
+exports.default = myFunc;