Always use the native (or polyfilled) Promise in transform-async-to-generator (#5536)

* Always use the native (or polyfilled) Promise in transform-async-to-generator

Fixes #5531

* Simplify scope handling to only un-shadow the Program's Promise

Only the helper needs to see the native Promise.

packages/babel-plugin-transform-async-to-generator/src/index.js

@@ -9,6 +9,13 @@ export default function () {
       Function(path, state) {
         if (!path.node.async || path.node.generator) return;
 
+        // Ensure any Promise bindings at the Program level are renamed
+        // so the asyncToGenerator helper only sees the native Promise
+        const programScope = path.scope.getProgramParent();
+        if (programScope.hasBinding("Promise", true)) {
+          programScope.rename("Promise");
+        }
+
         remapAsyncToGenerator(path, state.file, {
           wrapAsync: state.addHelper("asyncToGenerator"),
         });

packages/babel-plugin-transform-async-to-generator/test/fixtures/async-to-generator/shadowed-promise-import/actual.js

@@ -0,0 +1,5 @@
+import Promise from 'somewhere';
+
+async function foo() {
+  await Promise.resolve();
+}

packages/babel-plugin-transform-async-to-generator/test/fixtures/async-to-generator/shadowed-promise-import/expected.js

@@ -0,0 +1,13 @@
+let foo = (() => {
+  var _ref = _asyncToGenerator(function* () {
+    yield _Promise.resolve();
+  });
+
+  return function foo() {
+    return _ref.apply(this, arguments);
+  };
+})();
+
+function _asyncToGenerator(fn) { return function () { var gen = fn.apply(this, arguments); return new Promise(function (resolve, reject) { function step(key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then(function (value) { step("next", value); }, function (err) { step("throw", err); }); } } return step("next"); }); }; }
+
+import _Promise from 'somewhere';

packages/babel-plugin-transform-async-to-generator/test/fixtures/async-to-generator/shadowed-promise-import/options.json

@@ -0,0 +1,5 @@
+{
+  "plugins": [
+    "transform-async-to-generator"
+  ]
+}

packages/babel-plugin-transform-async-to-generator/test/fixtures/async-to-generator/shadowed-promise-nested/actual.js

@@ -0,0 +1,11 @@
+let Promise;
+
+async function foo() {
+  let Promise;
+
+  await bar();
+
+  async function bar() {
+    return Promise.resolve();
+  }
+}

packages/babel-plugin-transform-async-to-generator/test/fixtures/async-to-generator/shadowed-promise-nested/expected.js

@@ -0,0 +1,25 @@
+let foo = (() => {
+  var _ref = _asyncToGenerator(function* () {
+    let bar = (() => {
+      var _ref2 = _asyncToGenerator(function* () {
+        return Promise.resolve();
+      });
+
+      return function bar() {
+        return _ref2.apply(this, arguments);
+      };
+    })();
+
+    let Promise;
+
+    yield bar();
+  });
+
+  return function foo() {
+    return _ref.apply(this, arguments);
+  };
+})();
+
+function _asyncToGenerator(fn) { return function () { var gen = fn.apply(this, arguments); return new Promise(function (resolve, reject) { function step(key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then(function (value) { step("next", value); }, function (err) { step("throw", err); }); } } return step("next"); }); }; }
+
+let _Promise;

packages/babel-plugin-transform-async-to-generator/test/fixtures/async-to-generator/shadowed-promise-nested/options.json

@@ -0,0 +1,5 @@
+{
+  "plugins": [
+    "transform-async-to-generator"
+  ]
+}

packages/babel-plugin-transform-async-to-generator/test/fixtures/async-to-generator/shadowed-promise/actual.js

@@ -0,0 +1,4 @@
+let Promise;
+async function foo() {
+  await new Promise(resolve => { resolve() });
+}

packages/babel-plugin-transform-async-to-generator/test/fixtures/async-to-generator/shadowed-promise/expected.js

@@ -0,0 +1,15 @@
+let foo = (() => {
+  var _ref = _asyncToGenerator(function* () {
+    yield new _Promise(function (resolve) {
+      resolve();
+    });
+  });
+
+  return function foo() {
+    return _ref.apply(this, arguments);
+  };
+})();
+
+function _asyncToGenerator(fn) { return function () { var gen = fn.apply(this, arguments); return new Promise(function (resolve, reject) { function step(key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then(function (value) { step("next", value); }, function (err) { step("throw", err); }); } } return step("next"); }); }; }
+
+let _Promise;

packages/babel-plugin-transform-async-to-generator/test/fixtures/async-to-generator/shadowed-promise/options.json

@@ -0,0 +1,5 @@
+{
+  "plugins": [
+    "transform-async-to-generator"
+  ]
+}