fix: handle decorated async private method and generator (babel#16258)

packages/babel-helper-create-class-features-plugin/src/decorators.ts

@@ -634,12 +634,6 @@ function addCallAccessorsFor(
   );
 }
 
-function isNotTsParameter(
-  node: t.Identifier | t.Pattern | t.RestElement | t.TSParameterProperty,
-): node is t.Identifier | t.Pattern | t.RestElement {
-  return node.type !== "TSParameterProperty";
-}
-
 function movePrivateAccessor(
   element: NodePath<t.ClassPrivateMethod>,
   key: t.PrivateName,
@@ -702,6 +696,25 @@ function maybeSequenceExpression(exprs: t.Expression[]) {
   return t.sequenceExpression(exprs);
 }
 
+/**
+ * Create FunctionExpression from a ClassPrivateMethod.
+ * The returned FunctionExpression node takes ownership of the private method's body and params.
+ *
+ * @param {t.ClassPrivateMethod} node
+ * @returns
+ */
+function createFunctionExpressionFromPrivateMethod(node: t.ClassPrivateMethod) {
+  const { params, body, generator: isGenerator, async: isAsync } = node;
+  return t.functionExpression(
+    undefined,
+    // @ts-expect-error todo: Improve typings: TSParameterProperty is only allowed in constructor
+    params,
+    body,
+    isGenerator,
+    isAsync,
+  );
+}
+
 function createSetFunctionNameCall(
   state: PluginPass,
   className: t.Identifier | t.StringLiteral,
@@ -1122,18 +1135,9 @@ function transformClass(
 
           replaceSupers.replace();
 
-          const {
-            params,
-            body,
-            async: isAsync,
-          } = element.node as t.ClassPrivateMethod;
-
           privateMethods = [
-            t.functionExpression(
-              undefined,
-              params.filter(isNotTsParameter),
-              body,
-              isAsync,
+            createFunctionExpressionFromPrivateMethod(
+              element.node as t.ClassPrivateMethod,
             ),
           ];
 

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-methods--to-es2015/private-async-and-generator/exec.js

@@ -0,0 +1,23 @@
+let counter = 0;
+
+class Foo {
+  @(function (fn) {
+    counter++;
+    expect(fn.constructor.name).toBe("AsyncFunction");
+  })
+  async #a() {}
+
+  @(function (fn) {
+    counter++;
+    expect(fn.constructor.name).toBe("GeneratorFunction");
+  })
+  *#g() {}
+
+  @(function (fn) {
+    counter++;
+    expect(fn.constructor.name).toBe("AsyncGeneratorFunction");
+  })
+  async *#ag() {}
+}
+
+expect(counter).toBe(3);

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-methods--to-es2015/private-async-and-generator/input.js

@@ -0,0 +1,10 @@
+class Foo {
+  @dec
+  async #a() {}
+
+  @dec
+  *#g() {}
+
+  @dec
+  async *#ag() {}
+}

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-methods--to-es2015/private-async-and-generator/options.json

@@ -0,0 +1,3 @@
+{
+  "minNodeVersion": "10.0.0"
+}

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-methods--to-es2015/private-async-and-generator/output.js

@@ -0,0 +1,26 @@
+var _initProto, _dec, _call_a, _dec2, _call_g, _dec3, _call_ag, _Foo;
+_dec = dec;
+_dec2 = dec;
+_dec3 = dec;
+var _ag = /*#__PURE__*/new WeakMap();
+var _g = /*#__PURE__*/new WeakMap();
+var _a = /*#__PURE__*/new WeakMap();
+class Foo {
+  constructor() {
+    babelHelpers.classPrivateFieldInitSpec(this, _ag, {
+      writable: true,
+      value: _call_ag
+    });
+    babelHelpers.classPrivateFieldInitSpec(this, _g, {
+      writable: true,
+      value: _call_g
+    });
+    babelHelpers.classPrivateFieldInitSpec(this, _a, {
+      writable: true,
+      value: _call_a
+    });
+    _initProto(this);
+  }
+}
+_Foo = Foo;
+[_call_a, _call_g, _call_ag, _initProto] = babelHelpers.applyDecs2311(_Foo, [[_dec, 2, "a", async function () {}], [_dec2, 2, "g", function* () {}], [_dec3, 2, "ag", async function* () {}]], [], 0, _ => _a.has(babelHelpers.checkInRHS(_))).e;

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-methods/private-async-and-generator/exec.js

@@ -0,0 +1,23 @@
+let counter = 0;
+
+class Foo {
+  @(function (fn) {
+    counter++;
+    expect(fn.constructor.name).toBe("AsyncFunction");
+  })
+  async #a() {}
+
+  @(function (fn) {
+    counter++;
+    expect(fn.constructor.name).toBe("GeneratorFunction");
+  })
+  *#g() {}
+
+  @(function (fn) {
+    counter++;
+    expect(fn.constructor.name).toBe("AsyncGeneratorFunction");
+  })
+  async *#ag() {}
+}
+
+expect(counter).toBe(3);

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-methods/private-async-and-generator/input.js

@@ -0,0 +1,10 @@
+class Foo {
+  @dec
+  async #a() {}
+
+  @dec
+  *#g() {}
+
+  @dec
+  async *#ag() {}
+}

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-methods/private-async-and-generator/options.json

@@ -0,0 +1,3 @@
+{
+  "minNodeVersion": "16.11.0"
+}

packages/babel-plugin-proposal-decorators/test/fixtures/2023-11-methods/private-async-and-generator/output.js

@@ -0,0 +1,15 @@
+var _initProto, _dec, _call_a, _dec2, _call_g, _dec3, _call_ag;
+_dec = dec;
+_dec2 = dec;
+_dec3 = dec;
+class Foo {
+  static {
+    [_call_a, _call_g, _call_ag, _initProto] = babelHelpers.applyDecs2311(this, [[_dec, 2, "a", async function () {}], [_dec2, 2, "g", function* () {}], [_dec3, 2, "ag", async function* () {}]], [], 0, _ => #a in _).e;
+  }
+  constructor() {
+    _initProto(this);
+  }
+  #ag = _call_ag;
+  #g = _call_g;
+  #a = _call_a;
+}