Implement transform support for using declarations

packages/babel-helpers/src/helpers-generated.ts

@@ -91,7 +91,7 @@ export default Object.freeze({
   ),
   using: helper(
     "7.0.0-beta.0",
-    'export default function _using(stack,value,isAwait){if(null!=value){if(isAwait)var dispose=value[Symbol.asyncDispose||Symbol.for("Symbol.asyncDispose")];if(null==dispose&&(dispose=value[Symbol.dispose||Symbol.for("Symbol.dispose")]),"function"!=typeof dispose)throw new TypeError("Property [Symbol.dispose] is not a function.");stack.push({v:value,d:dispose,a:isAwait})}return value}',
+    'export default function _using(stack,value,isAwait){if(null==value)return value;if("object"!=typeof value)throw new TypeError("using decarations can only be used with objects, null, or undefined.");if(isAwait)var dispose=value[Symbol.asyncDispose||Symbol.for("Symbol.asyncDispose")];if(null==dispose&&(dispose=value[Symbol.dispose||Symbol.for("Symbol.dispose")]),"function"!=typeof dispose)throw new TypeError("Property [Symbol.dispose] is not a function.");return stack.push({v:value,d:dispose,a:isAwait}),value}',
   ),
   wrapRegExp: helper(
     "7.19.0",

packages/babel-helpers/src/helpers/using.js

@@ -1,19 +1,23 @@
 /* @minVersion 7.0.0-beta.0 */
 
 export default function _using(stack, value, isAwait) {
-  if (value !== null && value !== void 0) {
-    // core-js-pure uses Symbol.for for polyfilling well-known symbols
-    if (isAwait) {
-      var dispose =
-        value[Symbol.asyncDispose || Symbol.for("Symbol.asyncDispose")];
-    }
-    if (dispose === null || dispose === void 0) {
-      dispose = value[Symbol.dispose || Symbol.for("Symbol.dispose")];
-    }
-    if (typeof dispose !== "function") {
-      throw new TypeError(`Property [Symbol.dispose] is not a function.`);
-    }
-    stack.push({ v: value, d: dispose, a: isAwait });
+  if (value === null || value === void 0) return value;
+  if (typeof value !== "object") {
+    throw new TypeError(
+      "using decarations can only be used with objects, null, or undefined."
+    );
   }
+  // core-js-pure uses Symbol.for for polyfilling well-known symbols
+  if (isAwait) {
+    var dispose =
+      value[Symbol.asyncDispose || Symbol.for("Symbol.asyncDispose")];
+  }
+  if (dispose === null || dispose === void 0) {
+    dispose = value[Symbol.dispose || Symbol.for("Symbol.dispose")];
+  }
+  if (typeof dispose !== "function") {
+    throw new TypeError(`Property [Symbol.dispose] is not a function.`);
+  }
+  stack.push({ v: value, d: dispose, a: isAwait });
   return value;
 }

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/exec-async/async-dispose-throws-synchronously.js

@@ -0,0 +1,19 @@
+return async function () {
+  let disposed = false;
+  let beforeEnd;
+
+  const err = {};
+  let thrown;
+
+  try {
+    await using x = {
+      async [Symbol.asyncDispose || Symbol.for("Symbol.asyncDispose")]() {
+        throw err;
+      }
+    };
+  } catch (e) {
+    thrown = e;
+  }
+
+  expect(thrown).toBe(err);
+}();

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/exec-sync/invalid-not-object.js

@@ -0,0 +1,3 @@
+expect(() => {
+  using x = 2;
+}).toThrow(TypeError);

packages/babel-plugin-proposal-explicit-resource-management/test/fixtures/exec-sync/using-null.js

@@ -1,3 +1,4 @@
 expect(() => {
   using x = null;
+  using y = undefined;
 }).not.toThrow();