Implement noCallClass assumption

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

@@ -341,6 +341,7 @@ export const assumptionsNames = new Set<string>([
   "iterableIsArray",
   "mutableTemplateObject",
   "newableArrowFunctions",
+  "noCallClass",
   "noDocumentAll",
   "objectRestNoSymbols",
   "privateFieldsAsProperties",

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

@@ -25,6 +25,7 @@ export default declare((api, options) => {
   const constantSuper = api.assumption("constantSuper") ?? options.loose;
   const superIsCallableConstructor =
     api.assumption("superIsCallableConstructor") ?? options.loose;
+  const noCallClass = api.assumption("noCallClass") ?? options.loose;
 
   // todo: investigate traversal requeueing
   const VISITED = Symbol();
@@ -67,6 +68,7 @@ export default declare((api, options) => {
             setClassMethods,
             constantSuper,
             superIsCallableConstructor,
+            noCallClass,
           }),
         );
 

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

@@ -15,6 +15,7 @@ type ClassAssumptions = {
   setClassMethods: boolean,
   constantSuper: boolean,
   superIsCallableConstructor: boolean,
+  noCallClass: boolean,
 };
 
 function buildConstructor(classRef, constructorBody, node) {
@@ -670,7 +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.noCallClass) {
       constructorBody.body.unshift(
         t.expressionStatement(
           t.callExpression(classState.file.addHelper("classCallCheck"), [

packages/babel-plugin-transform-classes/test/fixtures/assumption-noCallClass/class/input.js

@@ -0,0 +1 @@
+class A {}

packages/babel-plugin-transform-classes/test/fixtures/assumption-noCallClass/class/output.js

@@ -0,0 +1,3 @@
+var A = function A() {
+  "use strict";
+};

packages/babel-plugin-transform-classes/test/fixtures/assumption-noCallClass/options.json

@@ -0,0 +1,12 @@
+{
+  "plugins": [
+    ["external-helpers", { "helperVersion": "7.100.0" }],
+    "transform-function-name",
+    "transform-classes",
+    ["transform-spread", { "loose": true }],
+    "transform-block-scoping"
+  ],
+  "assumptions": {
+    "noCallClass": true
+  }
+}

packages/babel-plugin-transform-classes/test/fixtures/assumption-noCallClass/with-constructor/input.js

@@ -0,0 +1,11 @@
+class A {
+  constructor() {
+    console.log('a');
+  }
+}
+
+class B {
+  b() {
+    console.log('b');
+  }
+}

packages/babel-plugin-transform-classes/test/fixtures/assumption-noCallClass/with-constructor/output.js

@@ -0,0 +1,19 @@
+var A = function A() {
+  "use strict";
+
+  console.log('a');
+};
+
+var B = /*#__PURE__*/function () {
+  "use strict";
+
+  function B() {}
+
+  babelHelpers.createClass(B, [{
+    key: "b",
+    value: function b() {
+      console.log('b');
+    }
+  }]);
+  return B;
+}();

packages/babel-plugin-transform-classes/test/fixtures/assumption-noCallClass/with-superClass/input.js

@@ -0,0 +1,8 @@
+class B {}
+
+class A extends B {
+  constructor(track) {
+    if (track !== undefined) super(track);
+    else super();
+  }
+}

packages/babel-plugin-transform-classes/test/fixtures/assumption-noCallClass/with-superClass/output.js

@@ -0,0 +1,20 @@
+var B = function B() {
+  "use strict";
+};
+
+var A = /*#__PURE__*/function (_B) {
+  "use strict";
+
+  babelHelpers.inherits(A, _B);
+
+  var _super = babelHelpers.createSuper(A);
+
+  function A(track) {
+    var _this;
+
+    if (track !== undefined) _this = _super.call(this, track);else _this = _super.call(this);
+    return babelHelpers.possibleConstructorReturn(_this);
+  }
+
+  return A;
+}(B);