Support ES6's "new function" construct

This resolves #75.

Merged remote-tracking branch 'janek/js_function_new_1'

2 files changed, 110 insertions, 0 deletions

diff --git a/js/src/tests/ecma_2017/AsyncFunctions/construct-newtarget.js b/js/src/tests/ecma_2017/AsyncFunctions/construct-newtarget.js
new file mode 100644
index 000000000..7d75d0c93
--- /dev/null
+++ b/js/src/tests/ecma_2017/AsyncFunctions/construct-newtarget.js
@@ -0,0 +1,79 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const AsyncFunction = async function(){}.constructor;
+
+
+// Test subclassing %AsyncFunction% works correctly.
+class MyAsync extends AsyncFunction {}
+
+var fn = new MyAsync();
+assertEq(fn instanceof MyAsync, true);
+assertEq(fn instanceof AsyncFunction, true);
+assertEq(Object.getPrototypeOf(fn), MyAsync.prototype);
+
+fn = Reflect.construct(MyAsync, []);
+assertEq(fn instanceof MyAsync, true);
+assertEq(fn instanceof AsyncFunction, true);
+assertEq(Object.getPrototypeOf(fn), MyAsync.prototype);
+
+fn = Reflect.construct(MyAsync, [], MyAsync);
+assertEq(fn instanceof MyAsync, true);
+assertEq(fn instanceof AsyncFunction, true);
+assertEq(Object.getPrototypeOf(fn), MyAsync.prototype);
+
+fn = Reflect.construct(MyAsync, [], AsyncFunction);
+assertEq(fn instanceof MyAsync, false);
+assertEq(fn instanceof AsyncFunction, true);
+assertEq(Object.getPrototypeOf(fn), AsyncFunction.prototype);
+
+
+// Set a different constructor as NewTarget.
+fn = Reflect.construct(MyAsync, [], Array);
+assertEq(fn instanceof MyAsync, false);
+assertEq(fn instanceof AsyncFunction, false);
+assertEq(Object.getPrototypeOf(fn), Array.prototype);
+
+fn = Reflect.construct(AsyncFunction, [], Array);
+assertEq(fn instanceof AsyncFunction, false);
+assertEq(Object.getPrototypeOf(fn), Array.prototype);
+
+
+// The prototype defaults to %AsyncFunctionPrototype% if null.
+function NewTargetNullPrototype() {}
+NewTargetNullPrototype.prototype = null;
+
+fn = Reflect.construct(AsyncFunction, [], NewTargetNullPrototype);
+assertEq(fn instanceof AsyncFunction, true);
+assertEq(Object.getPrototypeOf(fn), AsyncFunction.prototype);
+
+fn = Reflect.construct(MyAsync, [], NewTargetNullPrototype);
+assertEq(fn instanceof MyAsync, false);
+assertEq(fn instanceof AsyncFunction, true);
+assertEq(Object.getPrototypeOf(fn), AsyncFunction.prototype);
+
+
+// "prototype" property is retrieved exactly once.
+var trapLog = [], getLog = [];
+var ProxiedConstructor = new Proxy(AsyncFunction, new Proxy({
+    get(target, propertyKey, receiver) {
+        getLog.push(propertyKey);
+        return Reflect.get(target, propertyKey, receiver);
+    }
+}, {
+    get(target, propertyKey, receiver) {
+        trapLog.push(propertyKey);
+        return Reflect.get(target, propertyKey, receiver);
+    }
+}));
+
+fn = Reflect.construct(AsyncFunction, [], ProxiedConstructor);
+assertEqArray(trapLog, ["get"]);
+assertEqArray(getLog, ["prototype"]);
+assertEq(fn instanceof AsyncFunction, true);
+assertEq(Object.getPrototypeOf(fn), AsyncFunction.prototype);
+
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0);
diff --git a/js/src/tests/ecma_2017/AsyncFunctions/subclass.js b/js/src/tests/ecma_2017/AsyncFunctions/subclass.js
new file mode 100644
index 000000000..da20ab19b
--- /dev/null
+++ b/js/src/tests/ecma_2017/AsyncFunctions/subclass.js
@@ -0,0 +1,31 @@
+// |reftest| skip-if(!xulRuntime.shell) -- needs drainJobQueue
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const AsyncFunction = async function(){}.constructor;
+
+class MyAsync extends AsyncFunction {}
+
+// MyGen inherits from %AsyncFunction%.
+assertEq(Object.getPrototypeOf(MyAsync), AsyncFunction);
+
+// MyGen.prototype inherits from %AsyncFunctionPrototype%.
+assertEq(Object.getPrototypeOf(MyAsync.prototype), AsyncFunction.prototype);
+
+var fn = new MyAsync("return await 'ok';");
+
+// fn inherits from MyAsync.prototype.
+assertEq(Object.getPrototypeOf(fn), MyAsync.prototype);
+
+// Ensure the new async function can be executed.
+var promise = fn();
+
+// promise inherits from %Promise.prototype%.
+assertEq(Object.getPrototypeOf(promise), Promise.prototype);
+
+// Computes the expected result.
+assertEventuallyEq(promise, "ok");
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0);