fix async function remap helper from outputing incorrect calls causing wrong scoping - fixes #2708 - fixes #2715

CHANGELOG.md

@@ -13,6 +13,11 @@ _Note: Gaps between patch versions are faulty, broken or test releases._
 
 See [CHANGELOG - 6to5](CHANGELOG-6to5.md) for the pre-4.0.0 version changelog.
 
+## 6.0.15
+
+ * **Bug Fix**
+  * Fix async function remap helper from outputing incorrect calls causing wrong scoping.
+
 ## 6.0.14
 
  * **Spec Compliancy**

packages/babel-core/test/fixtures/transformation/async-to-generator/expression/expected.js

@@ -1,5 +1,8 @@
-var foo = function () {
-  return babelHelpers.asyncToGenerator(function* () {
+var foo = (function () {
+  var ref = babelHelpers.asyncToGenerator(function* () {
     var wat = yield bar();
-  })();
-};
+  });
+  return function foo() {
+    return ref.apply(this, arguments);
+  };
+})();

packages/babel-core/test/fixtures/transformation/async-to-generator/named-expression/actual.js

@@ -1,5 +1,3 @@
 var foo = async function bar() {
   console.log(bar);
 };
-
-foo();

packages/babel-core/test/fixtures/transformation/async-to-generator/named-expression/expected.js

@@ -1,7 +1,8 @@
-var foo = function () {
-  return babelHelpers.asyncToGenerator(function* bar() {
+var foo = (function () {
+  var ref = babelHelpers.asyncToGenerator(function* bar() {
     console.log(bar);
-  })();
-};
-
-foo();
+  });
+  return function foo() {
+    return ref.apply(this, arguments);
+  };
+})();

packages/babel-core/test/fixtures/transformation/async-to-generator/no-parameters-and-no-id/actual.js

@@ -0,0 +1,3 @@
+foo(async function () {
+  
+});

packages/babel-core/test/fixtures/transformation/async-to-generator/no-parameters-and-no-id/expected.js

@@ -0,0 +1 @@
+foo(babelHelpers.asyncToGenerator(function* () {}));

packages/babel-core/test/fixtures/transformation/async-to-generator/parameters/actual.js

@@ -0,0 +1,3 @@
+async function foo(bar) {
+
+}

packages/babel-core/test/fixtures/transformation/async-to-generator/parameters/expected.js

@@ -0,0 +1,6 @@
+let foo = (function () {
+  var ref = babelHelpers.asyncToGenerator(function* foo(bar) {});
+  return function foo(_x) {
+    return ref.apply(this, arguments);
+  };
+})();

packages/babel-core/test/fixtures/transformation/async-to-generator/statement/expected.js

@@ -1,5 +1,8 @@
-let foo = function foo() {
-  return babelHelpers.asyncToGenerator(function* foo() {
+let foo = (function () {
+  var ref = babelHelpers.asyncToGenerator(function* foo() {
     var wat = yield bar();
-  })();
-};
+  });
+  return function foo() {
+    return ref.apply(this, arguments);
+  };
+})();

packages/babel-core/test/fixtures/transformation/bluebird-coroutines/expression/expected.js

@@ -1,6 +1,10 @@
 import { coroutine as _coroutine } from "bluebird";
-var foo = function () {
-  return _coroutine(function* () {
+var foo = (function () {
+  var ref = _coroutine(function* () {
     var wat = yield bar();
-  })();
-};
+  });
+
+  return function foo() {
+    return ref.apply(this, arguments);
+  };
+})();

packages/babel-core/test/fixtures/transformation/bluebird-coroutines/named-expression/actual.js

@@ -1,5 +1,3 @@
 var foo = async function bar() {
   console.log(bar);
 };
-
-foo();

packages/babel-core/test/fixtures/transformation/bluebird-coroutines/named-expression/expected.js

@@ -1,8 +1,10 @@
 import { coroutine as _coroutine } from "bluebird";
-var foo = function () {
-  return _coroutine(function* bar() {
+var foo = (function () {
+  var ref = _coroutine(function* bar() {
     console.log(bar);
-  })();
-};
+  });
 
-foo();
+  return function foo() {
+    return ref.apply(this, arguments);
+  };
+})();

packages/babel-core/test/fixtures/transformation/bluebird-coroutines/statement/expected.js

@@ -1,7 +1,11 @@
 import { coroutine as _coroutine } from "bluebird";
 
-let foo = function foo() {
-  return _coroutine(function* foo() {
+let foo = (function () {
+  var ref = _coroutine(function* foo() {
     var wat = yield bar();
-  })();
-};
+  });
+
+  return function foo() {
+    return ref.apply(this, arguments);
+  };
+})();

packages/babel-helper-remap-async-to-generator/package.json

@@ -7,8 +7,9 @@
   "main": "lib/index.js",
   "dependencies": {
     "babel-runtime": "^5.0.0",
+    "babel-template": "^6.0.14",
     "babel-types": "^6.0.14",
     "babel-traverse": "^6.0.14",
     "babel-helper-function-name": "^6.0.14"
   }
-}
+}

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

@@ -2,8 +2,18 @@
 
 import type { NodePath } from "babel-traverse";
 import nameFunction from "babel-helper-function-name";
+import template from "babel-template";
 import * as t from "babel-types";
 
+let buildWrapper = template(`
+  (function () {
+    var ref = FUNCTION;
+    return function (PARAMS) {
+      return ref.apply(this, arguments);
+    };
+  })
+`);
+
 let awaitVisitor = {
   Function(path) {
     path.skip();
@@ -14,45 +24,78 @@ let awaitVisitor = {
   }
 };
 
-export default function (path: NodePath, callId: Object) {
+function classMethod(path: NodePath, callId: Object) {
   let node = path.node;
-  if (node.generator) return;
+  let body = node.body;
 
-  if (path.isClassMethod()) {
-    node.async = false;
+  node.async = false;
 
-    let body = node.body;
+  let container = t.functionExpression(null, [], t.blockStatement(body.body), true);
+  container.shadow = true;
+  body.body = [
+    t.returnStatement(t.callExpression(
+      t.callExpression(callId, [container]),
+      []
+    ))
+  ];
+}
 
-    let container = t.functionExpression(null, [], t.blockStatement(body.body), true);
-    container.shadow = true;
-    body.body = [t.returnStatement(t.callExpression(t.callExpression(callId, [container]), []))];
-    return;
-  }
+function plainFunction(path: NodePath, callId: Object) {
+  let node = path.node;
 
   node.async = false;
   node.generator = true;
 
   path.traverse(awaitVisitor);
 
-  let container = t.functionExpression(null, [], t.blockStatement([
-    t.returnStatement(t.callExpression(t.callExpression(callId, [node]), []))
-  ]));
-  node.shadow = container;
+  let built = t.callExpression(callId, [node]);
+  let container = buildWrapper({
+    FUNCTION: built,
+    PARAMS: node.params.map(() => path.scope.generateUidIdentifier("x"))
+  }).expression;
+
+  let retFunction = container.body.body[1].argument;
 
   if (path.isFunctionDeclaration()) {
     let declar = t.variableDeclaration("let", [
-      t.variableDeclarator(t.identifier(node.id.name), container)
+      t.variableDeclarator(
+        t.identifier(node.id.name),
+        t.callExpression(container, [])
+      )
     ]);
     declar._blockHoist = true;
 
     nameFunction({
-      node: container,
+      node: retFunction,
       parent: declar.declarations[0],
       scope: path.scope
     });
 
     path.replaceWith(declar);
   } else {
-    path.replaceWith(container);
+    nameFunction({
+      node: retFunction,
+      parent: path.parent,
+      scope: path.scope
+    });
+
+    if (retFunction.id || node.params.length) {
+      // we have an inferred function id or params so we need this wrapper
+      path.replaceWith(t.callExpression(container, []));
+    } else {
+      // we can omit this wrapper as the conditions it protects for do not apply
+      path.replaceWith(built);
+    }
+  }
+}
+
+export default function (path: NodePath, callId: Object) {
+  let node = path.node;
+  if (node.generator) return;
+
+  if (path.isClassMethod()) {
+    return classMethod(path, callId);
+  } else {
+    return plainFunction(path, callId);
   }
 }