Add a bugfix plugin for https://crbug.com/v8/12421 (#14295)

Gulpfile.mjs

@@ -697,6 +697,7 @@ if (bool(process.env.BABEL_8_BREAKING)) {
     "packages/babel-preset-typescript",
     "packages/babel-helper-member-expression-to-functions",
     "packages/babel-plugin-bugfix-v8-spread-parameters-in-optional-chaining",
+    "packages/babel-plugin-bugfix-v8-static-class-fields-redefine-readonly",
     "packages/babel-plugin-bugfix-safari-id-destructuring-collision-in-function-expression",
   ].map(src => ({
     src,

packages/babel-compat-data/data/overlapping-plugins.json

@@ -21,5 +21,11 @@
   ],
   "proposal-optional-chaining": [
     "bugfix/transform-v8-spread-parameters-in-optional-chaining"
+  ],
+  "transform-class-properties": [
+    "bugfix/transform-v8-static-class-fields-redefine-readonly"
+  ],
+  "proposal-class-properties": [
+    "bugfix/transform-v8-static-class-fields-redefine-readonly"
   ]
 }

packages/babel-compat-data/data/plugins.json

@@ -10,6 +10,19 @@
     "opera_mobile": "75",
     "electron": "24.0"
   },
+  "bugfix/transform-v8-static-class-fields-redefine-readonly": {
+    "chrome": "98",
+    "opera": "84",
+    "edge": "98",
+    "firefox": "95",
+    "safari": "15",
+    "node": "12",
+    "deno": "1.18",
+    "ios": "15",
+    "samsung": "11",
+    "opera_mobile": "52",
+    "electron": "17.0"
+  },
   "transform-class-static-block": {
     "chrome": "94",
     "opera": "80",

packages/babel-compat-data/scripts/data/plugin-features.js

@@ -158,14 +158,16 @@ const es2021 = {
 };
 
 const es2022 = {
+  "bugfix/transform-v8-static-class-fields-redefine-readonly": {
+    features: ["static class fields / static class fields use [[Define]]"],
+    replaces: "transform-class-properties",
+  },
   "transform-class-static-block": "Class static initialization blocks",
   "transform-private-property-in-object":
     "Ergonomic brand checks for private fields",
   "transform-class-properties": {
     features: [
-      "static class fields / public static class fields",
-      "static class fields / private static class fields",
-      "static class fields / computed static class fields",
+      "static class fields",
       "instance class fields / public instance class fields",
       "instance class fields / private instance class fields basic support",
       "instance class fields / computed instance class fields",

packages/babel-plugin-bugfix-v8-static-class-fields-redefine-readonly/.npmignore

@@ -0,0 +1,3 @@
+src
+test
+*.log

packages/babel-plugin-bugfix-v8-static-class-fields-redefine-readonly/README.md

@@ -0,0 +1,19 @@
+# @babel/plugin-bugfix-v8-static-class-fields-redefine-readonly
+
+> Transform static class fields assignments that are affected by https://crbug.com/v8/12421
+
+See our website [@babel/plugin-bugfix-v8-static-class-fields-redefine-readonly](https://babeljs.io/docs/babel-plugin-bugfix-v8-static-class-fields-redefine-readonly) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save-dev @babel/plugin-bugfix-v8-static-class-fields-redefine-readonly
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/plugin-bugfix-v8-static-class-fields-redefine-readonly --dev
+```

packages/babel-plugin-bugfix-v8-static-class-fields-redefine-readonly/package.json

@@ -0,0 +1,57 @@
+{
+  "name": "@babel/plugin-bugfix-v8-static-class-fields-redefine-readonly",
+  "version": "7.16.7",
+  "description": "Transform static class fields assignments that are affected by https://crbug.com/v8/12421",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/babel/babel.git",
+    "directory": "packages/babel-plugin-bugfix-v8-static-class-fields-redefine-readonly"
+  },
+  "homepage": "https://babel.dev/docs/en/next/babel-plugin-bugfix-v8-static-class-fields-redefine-readonly",
+  "license": "MIT",
+  "publishConfig": {
+    "access": "public"
+  },
+  "main": "./lib/index.js",
+  "exports": {
+    ".": "./lib/index.js",
+    "./package.json": "./package.json"
+  },
+  "keywords": [
+    "babel-plugin",
+    "bugfix"
+  ],
+  "dependencies": {
+    "@babel/helper-environment-visitor": "workspace:^",
+    "@babel/helper-plugin-utils": "workspace:^"
+  },
+  "peerDependencies": {
+    "@babel/core": "^7.0.0"
+  },
+  "devDependencies": {
+    "@babel/core": "workspace:^",
+    "@babel/helper-plugin-test-runner": "workspace:^",
+    "@babel/traverse": "workspace:^"
+  },
+  "engines": {
+    "node": ">=6.9.0"
+  },
+  "author": "The Babel Team (https://babel.dev/team)",
+  "conditions": {
+    "USE_ESM": [
+      {
+        "type": "module"
+      },
+      null
+    ],
+    "BABEL_8_BREAKING": [
+      {
+        "engines": {
+          "node": "^16.20.0 || ^18.16.0 || >=20.0.0"
+        }
+      },
+      {}
+    ]
+  },
+  "type": "commonjs"
+}

packages/babel-plugin-bugfix-v8-static-class-fields-redefine-readonly/src/index.ts

@@ -0,0 +1,70 @@
+import type { NodePath, Scope } from "@babel/traverse";
+import { types as t, type PluginPass, type File } from "@babel/core";
+import { declare } from "@babel/helper-plugin-utils";
+
+import {
+  getPotentiallyBuggyFieldsIndexes,
+  getNameOrLengthStaticFieldsIndexes,
+  toRanges,
+} from "./util.ts";
+
+function buildFieldsReplacement(
+  fields: t.ClassProperty[],
+  scope: Scope,
+  file: File,
+) {
+  return t.staticBlock(
+    fields.map(field => {
+      const key =
+        field.computed || !t.isIdentifier(field.key)
+          ? field.key
+          : t.stringLiteral(field.key.name);
+
+      return t.expressionStatement(
+        t.callExpression(file.addHelper("defineProperty"), [
+          t.thisExpression(),
+          key,
+          field.value || scope.buildUndefinedNode(),
+        ]),
+      );
+    }),
+  );
+}
+
+export default declare(api => {
+  api.assertVersion(7);
+
+  const setPublicClassFields = api.assumption("setPublicClassFields");
+
+  return {
+    name: "bugfix-v8-static-class-fields-redefine-readonly",
+
+    visitor: {
+      Class(this: PluginPass, path: NodePath<t.Class>) {
+        const ranges = toRanges(
+          setPublicClassFields
+            ? getNameOrLengthStaticFieldsIndexes(path)
+            : getPotentiallyBuggyFieldsIndexes(path),
+        );
+
+        for (let i = ranges.length - 1; i >= 0; i--) {
+          const [start, end] = ranges[i];
+
+          const startPath = path.get("body.body")[start];
+
+          startPath.replaceWith(
+            buildFieldsReplacement(
+              path.node.body.body.slice(start, end) as t.ClassProperty[],
+              path.scope,
+              this.file,
+            ),
+          );
+
+          for (let j = end - 1; j > start; j--) {
+            path.get("body.body")[j].remove();
+          }
+        }
+      },
+    },
+  };
+});