Implement constantSuper, superIsCallableConstructor and `noClassC…

…alls` assumption (#12726)

Co-authored-by: Justin Ridgewell <justin@ridgewell.name>

packages/babel-core/src/config/validation/options.js

@@ -334,11 +334,13 @@ export type NestingPath = RootPath | OverridesPath | EnvPath;
 export const assumptionsNames = new Set<string>([
   "arrayLikeIsIterable",
   "constantReexports",
+  "constantSuper",
   "enumerableModuleMeta",
   "ignoreFunctionLength",
   "ignoreToPrimitiveHint",
   "iterableIsArray",
   "mutableTemplateObject",
+  "noClassCalls",
   "noDocumentAll",
   "noNewArrows",
   "objectRestNoSymbols",
@@ -349,6 +351,7 @@ export const assumptionsNames = new Set<string>([
   "setPublicClassFields",
   "setSpreadProperties",
   "skipForOfIteratorClosing",
+  "superIsCallableConstructor",
 ]);
 
 function getSource(loc: NestingPath): OptionsSource {

packages/babel-helper-create-class-features-plugin/src/fields.js

@@ -647,12 +647,12 @@ const thisContextVisitor = traverse.visitors.merge([
   environmentVisitor,
 ]);
 
-function replaceThisContext(path, ref, superRef, file, loose) {
+function replaceThisContext(path, ref, superRef, file, constantSuper) {
   const state = { classRef: ref, needsClassRef: false };
 
   const replacer = new ReplaceSupers({
     methodPath: path,
-    isLoose: loose,
+    constantSuper,
     superRef,
     file,
     refToPreserve: ref,
@@ -678,7 +678,7 @@ export function buildFieldsInitNodes(
   state,
   setPublicClassFields,
   privateFieldsAsProperties,
-  loose,
+  constantSuper,
 ) {
   const staticNodes = [];
   const instanceNodes = [];
@@ -695,7 +695,13 @@ export function buildFieldsInitNodes(
     const isMethod = !isField;
 
     if (isStatic || (isMethod && isPrivate)) {
-      const replaced = replaceThisContext(prop, ref, superRef, state, loose);
+      const replaced = replaceThisContext(
+        prop,
+        ref,
+        superRef,
+        state,
+        constantSuper,
+      );
       needsClassRef = needsClassRef || replaced;
     }
 

packages/babel-helper-create-class-features-plugin/src/index.js

@@ -41,6 +41,7 @@ export function createClassFeaturePlugin({
 }) {
   const setPublicClassFields = api.assumption("setPublicClassFields");
   const privateFieldsAsProperties = api.assumption("privateFieldsAsProperties");
+  const constantSuper = api.assumption("constantSuper");
   const noDocumentAll = api.assumption("noDocumentAll");
 
   if (loose) {
@@ -217,7 +218,7 @@ export function createClassFeaturePlugin({
             state,
             setPublicClassFields ?? loose,
             privateFieldsAsProperties ?? loose,
-            loose,
+            constantSuper ?? loose,
           ));
         }
 

packages/babel-helper-replace-supers/src/index.js

@@ -255,7 +255,7 @@ const looseHandlers = {
 type ReplaceSupersOptionsBase = {|
   methodPath: NodePath,
   superRef: Object,
-  isLoose: boolean,
+  constantSuper: boolean,
   file: any,
   // objectRef might have been shadowed in child scopes,
   // in that case, we need to rename related variables.
@@ -284,13 +284,16 @@ export default class ReplaceSupers {
 
     this.file = opts.file;
     this.superRef = opts.superRef;
-    this.isLoose = opts.isLoose;
+    this.constantSuper = process.env.BABEL_8_BREAKING
+      ? opts.constantSuper
+      : // Fallback to isLoose for backward compatibility
+        opts.constantSuper ?? (opts: any).isLoose;
     this.opts = opts;
   }
 
   declare file: HubInterface;
   declare isDerivedConstructor: boolean;
-  declare isLoose: boolean;
+  declare constantSuper: boolean;
   declare isPrivateMethod: boolean;
   declare isStatic: boolean;
   declare methodPath: NodePath;
@@ -309,7 +312,7 @@ export default class ReplaceSupers {
       });
     }
 
-    const handler = this.isLoose ? looseHandlers : specHandlers;
+    const handler = this.constantSuper ? looseHandlers : specHandlers;
 
     memberExpressionToFunctions(this.methodPath, visitor, {
       file: this.file,

packages/babel-plugin-proposal-private-methods/test/fixtures/assumption-constantSuper/options.json

@@ -0,0 +1,17 @@
+{
+  "plugins": [
+    [
+      "external-helpers",
+      {
+        "helperVersion": "7.1000.0"
+      }
+    ],
+    "proposal-private-methods",
+    "proposal-class-properties",
+    "transform-block-scoping",
+    "syntax-class-properties"
+  ],
+  "assumptions": {
+    "constantSuper": true
+  }
+}

packages/babel-plugin-proposal-private-methods/test/fixtures/assumption-constantSuper/private-method-super/input.js

@@ -0,0 +1,19 @@
+class Base {
+  superMethod() {
+    return 'good';
+  }
+}
+
+class Sub extends Base {
+  superMethod() {
+    return 'bad';
+  }
+
+  #privateMethod() {
+    return super.superMethod();
+  }
+
+  publicMethod() {
+    return this.#privateMethod();
+  }
+}

packages/babel-plugin-proposal-private-methods/test/fixtures/assumption-constantSuper/private-method-super/output.js

@@ -0,0 +1,29 @@
+class Base {
+  superMethod() {
+    return 'good';
+  }
+
+}
+
+var _privateMethod = new WeakSet();
+
+class Sub extends Base {
+  constructor(...args) {
+    super(...args);
+
+    _privateMethod.add(this);
+  }
+
+  superMethod() {
+    return 'bad';
+  }
+
+  publicMethod() {
+    return babelHelpers.classPrivateMethodGet(this, _privateMethod, _privateMethod2).call(this);
+  }
+
+}
+
+var _privateMethod2 = function _privateMethod2() {
+  return Base.prototype.superMethod.call(this);
+};

packages/babel-plugin-transform-classes/src/index.js

@@ -22,6 +22,10 @@ export default declare((api, options) => {
   const { loose } = options;
 
   const setClassMethods = api.assumption("setClassMethods") ?? options.loose;
+  const constantSuper = api.assumption("constantSuper") ?? options.loose;
+  const superIsCallableConstructor =
+    api.assumption("superIsCallableConstructor") ?? options.loose;
+  const noClassCalls = api.assumption("noClassCalls") ?? options.loose;
 
   // todo: investigate traversal requeueing
   const VISITED = Symbol();
@@ -62,6 +66,9 @@ export default declare((api, options) => {
         path.replaceWith(
           transformClass(path, state.file, builtinClasses, loose, {
             setClassMethods,
+            constantSuper,
+            superIsCallableConstructor,
+            noClassCalls,
           }),
         );
 

packages/babel-plugin-transform-classes/src/transformClass.js

@@ -11,7 +11,12 @@ import addCreateSuperHelper from "./inline-createSuper-helpers";
 
 type ReadonlySet<T> = Set<T> | { has(val: T): boolean };
 
-type ClassAssumptions = { setClassMethods: boolean };
+type ClassAssumptions = {
+  setClassMethods: boolean,
+  constantSuper: boolean,
+  superIsCallableConstructor: boolean,
+  noClassCalls: boolean,
+};
 
 function buildConstructor(classRef, constructorBody, node) {
   const func = t.functionDeclaration(
@@ -164,7 +169,7 @@ export default function transformClass(
           methodPath: path,
           objectRef: classState.classRef,
           superRef: classState.superName,
-          isLoose: classState.isLoose,
+          constantSuper: assumptions.constantSuper,
           file: classState.file,
           refToPreserve: classState.classRef,
         });
@@ -249,7 +254,7 @@ export default function transformClass(
     const bareSuperNode = bareSuper.node;
     let call;
 
-    if (classState.isLoose) {
+    if (assumptions.superIsCallableConstructor) {
       bareSuperNode.arguments.unshift(t.thisExpression());
       if (
         bareSuperNode.arguments.length === 2 &&
@@ -566,7 +571,7 @@ export default function transformClass(
     // Unshift to ensure that the constructor inheritance is set up before
     // any properties can be assigned to the prototype.
 
-    if (!classState.isLoose) {
+    if (!assumptions.superIsCallableConstructor) {
       classState.body.unshift(
         t.variableDeclaration("var", [
           t.variableDeclarator(
@@ -666,7 +671,7 @@ export default function transformClass(
     buildBody();
 
     // make sure this class isn't directly called (with A() instead new A())
-    if (!classState.isLoose) {
+    if (!assumptions.noClassCalls) {
       constructorBody.body.unshift(
         t.expressionStatement(
           t.callExpression(classState.file.addHelper("classCallCheck"), [

packages/babel-plugin-transform-classes/test/fixtures/assumption-constantSuper/accessing-super-class/input.js

@@ -0,0 +1,13 @@
+class Test extends Foo {
+  constructor() {
+    woops.super.test();
+    super();
+    super.test();
+
+    super(...arguments);
+    super("test", ...arguments);
+
+    super.test(...arguments);
+    super.test("test", ...arguments);
+  }
+}

packages/babel-plugin-transform-classes/test/fixtures/assumption-constantSuper/accessing-super-class/output.js

@@ -0,0 +1,30 @@
+var Test = /*#__PURE__*/function (_Foo) {
+  "use strict";
+
+  babelHelpers.inherits(Test, _Foo);
+
+  var _super = babelHelpers.createSuper(Test);
+
+  function Test() {
+    var _Foo$prototype$test;
+
+    var _this;
+
+    babelHelpers.classCallCheck(this, Test);
+    woops.super.test();
+    _this = _super.call(this);
+
+    _Foo.prototype.test.call(babelHelpers.assertThisInitialized(_this));
+
+    _this = _super.apply(this, arguments);
+    _this = _super.call.apply(_super, [this, "test"].concat(Array.prototype.slice.call(arguments)));
+
+    _Foo.prototype.test.apply(babelHelpers.assertThisInitialized(_this), arguments);
+
+    (_Foo$prototype$test = _Foo.prototype.test).call.apply(_Foo$prototype$test, [babelHelpers.assertThisInitialized(_this), "test"].concat(Array.prototype.slice.call(arguments)));
+
+    return _this;
+  }
+
+  return Test;
+}(Foo);

packages/babel-plugin-transform-classes/test/fixtures/assumption-constantSuper/accessing-super-properties/input.js

@@ -0,0 +1,7 @@
+class Test extends Foo {
+  constructor() {
+    super();
+    super.test;
+    super.test.whatever;
+  }
+}

packages/babel-plugin-transform-classes/test/fixtures/assumption-constantSuper/accessing-super-properties/output.js

@@ -0,0 +1,19 @@
+var Test = /*#__PURE__*/function (_Foo) {
+  "use strict";
+
+  babelHelpers.inherits(Test, _Foo);
+
+  var _super = babelHelpers.createSuper(Test);
+
+  function Test() {
+    var _this;
+
+    babelHelpers.classCallCheck(this, Test);
+    _this = _super.call(this);
+    _Foo.prototype.test;
+    _Foo.prototype.test.whatever;
+    return _this;
+  }
+
+  return Test;
+}(Foo);

packages/babel-plugin-transform-classes/test/fixtures/assumption-constantSuper/accessing-super-property-optional-chain/input.js

@@ -0,0 +1,6 @@
+class Test extends Foo {
+  constructor() {
+    super.foo?.bar;
+    super.foo?.();
+  }
+}

packages/babel-plugin-transform-classes/test/fixtures/assumption-constantSuper/accessing-super-property-optional-chain/options.json

@@ -0,0 +1,10 @@
+{
+  "plugins": [
+    ["external-helpers", { "helperVersion": "7.100.0" }],
+    ["proposal-optional-chaining", { "loose": true }],
+    "transform-function-name",
+    ["transform-classes", { "loose": true }],
+    ["transform-spread", { "loose": true }],
+    "transform-block-scoping"
+  ]
+}

packages/babel-plugin-transform-classes/test/fixtures/assumption-constantSuper/accessing-super-property-optional-chain/output.js

@@ -0,0 +1,17 @@
+var Test = /*#__PURE__*/function (_Foo) {
+  "use strict";
+
+  babelHelpers.inheritsLoose(Test, _Foo);
+
+  function Test() {
+    var _Foo$prototype$foo, _Foo$prototype$foo2;
+
+    var _this;
+
+    (_Foo$prototype$foo = _Foo.prototype.foo) == null ? void 0 : _Foo$prototype$foo.bar;
+    (_Foo$prototype$foo2 = _Foo.prototype.foo) == null ? void 0 : _Foo$prototype$foo2.call(babelHelpers.assertThisInitialized(_this));
+    return babelHelpers.assertThisInitialized(_this);
+  }
+
+  return Test;
+}(Foo);

packages/babel-plugin-transform-classes/test/fixtures/assumption-constantSuper/calling-super-properties/input.js

@@ -0,0 +1,11 @@
+class Test extends Foo {
+  constructor() {
+    super();
+    super.test.whatever();
+    super.test();
+  }
+
+  static test() {
+    return super.wow();
+  }
+}