Add transform to rename variables that are ES3 reserved words (#6479)

* Initial version

* Replace .includes with .indexOf and better node set to visit

* Alphabetically sort es3 reserved words and make difference helper for readability

* Fix second Array.include error that was not polyfilled

* Move es3 keywords into separate babel-types helper and use in all es3 transforms

* Reference local plugin build directly for tests

* Try relative import for babel-types

* Update to scoped package name and beta 3

* Fix unscoped package import

* Replace local plugin reference with proper plugin name

packages/babel-plugin-transform-es3-member-expression-literals/src/index.js

@@ -7,7 +7,7 @@ export default function({ types: t }) {
           if (
             !node.computed &&
             t.isIdentifier(prop) &&
-            !t.isValidIdentifier(prop.name)
+            !t.isValidES3Identifier(prop.name)
           ) {
             // foo.default -> foo["default"]
             node.property = t.stringLiteral(prop.name);

packages/babel-plugin-transform-es3-property-literals/src/index.js

@@ -7,7 +7,7 @@ export default function({ types: t }) {
           if (
             !node.computed &&
             t.isIdentifier(key) &&
-            !t.isValidIdentifier(key.name)
+            !t.isValidES3Identifier(key.name)
           ) {
             // default: "bar" -> "default": "bar"
             node.key = t.stringLiteral(key.name);

packages/babel-plugin-transform-es3-reserved-words/.npmignore

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

packages/babel-plugin-transform-es3-reserved-words/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "@babel/plugin-transform-es3-reserved-words",
+  "version": "7.0.0-beta.3",
+  "description": "Ensure that no reserved words are used.",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-transform-es3-reserved-words",
+  "license": "MIT",
+  "main": "lib/index.js",
+  "keywords": [
+    "babel-plugin"
+  ],
+  "devDependencies": {
+    "@babel/helper-plugin-test-runner": "7.0.0-beta.3"
+  }
+}

packages/babel-plugin-transform-es3-reserved-words/src/index.js

@@ -0,0 +1,11 @@
+export default function({ types: t }) {
+  return {
+    visitor: {
+      "BindingIdentifier|ReferencedIdentifier"(path) {
+        if (!t.isValidES3Identifier(path.node.name)) {
+          path.scope.rename(path.node.name);
+        }
+      },
+    },
+  };
+}

packages/babel-plugin-transform-es3-reserved-words/test/fixtures/issue-6477/issue-6477/actual.js

@@ -0,0 +1,4 @@
+function utf8CheckByte(byte) {
+  if (byte <= 0x7F) return 0;else if (byte >> 5 === 0x06) return 2;else if (byte >> 4 === 0x0E) return 3;else if (byte >> 3 === 0x1E) return 4;
+  return -1;
+}

packages/babel-plugin-transform-es3-reserved-words/test/fixtures/issue-6477/issue-6477/expected.js

@@ -0,0 +1,4 @@
+function utf8CheckByte(_byte) {
+  if (_byte <= 0x7F) return 0;else if (_byte >> 5 === 0x06) return 2;else if (_byte >> 4 === 0x0E) return 3;else if (_byte >> 3 === 0x1E) return 4;
+  return -1;
+}

packages/babel-plugin-transform-es3-reserved-words/test/fixtures/issue-6477/issue-6477/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-es3-reserved-words"]
+}

packages/babel-plugin-transform-es3-reserved-words/test/index.js

@@ -0,0 +1,3 @@
+import runner from "@babel/helper-plugin-test-runner";
+
+runner(__dirname);

packages/babel-types/src/constants.js

@@ -62,3 +62,30 @@ export const BLOCK_SCOPED_SYMBOL = Symbol.for("var used to be block scoped");
 export const NOT_LOCAL_BINDING = Symbol.for(
   "should not be considered a local binding",
 );
+
+export const RESERVED_WORDS_ES3_ONLY = new Set([
+  "abstract",
+  "boolean",
+  "byte",
+  "char",
+  "double",
+  "enum",
+  "final",
+  "float",
+  "goto",
+  "implements",
+  "int",
+  "interface",
+  "long",
+  "native",
+  "package",
+  "private",
+  "protected",
+  "public",
+  "short",
+  "static",
+  "synchronized",
+  "throws",
+  "transient",
+  "volatile",
+]);

packages/babel-types/src/index.js

@@ -580,6 +580,7 @@ export {
   isBinding,
   isReferenced,
   isValidIdentifier,
+  isValidES3Identifier,
   isLet,
   isBlockScoped,
   isVar,

packages/babel-types/src/validators.js

@@ -1,7 +1,7 @@
 import { getBindingIdentifiers } from "./retrievers";
 import esutils from "esutils";
 import * as t from "./index";
-import { BLOCK_SCOPED_SYMBOL } from "./constants";
+import { BLOCK_SCOPED_SYMBOL, RESERVED_WORDS_ES3_ONLY } from "./constants";
 
 /**
  * Check if the input `node` is a binding identifier.
@@ -177,6 +177,14 @@ export function isValidIdentifier(name: string): boolean {
     return esutils.keyword.isIdentifierNameES6(name);
   }
 }
+/**
+ * Check if the input `name` is a valid identifier name according to the ES3 specification.
+ *
+ * Additional ES3 reserved words are
+ */
+export function isValidES3Identifier(name: string): boolean {
+  return isValidIdentifier(name, true) && !RESERVED_WORDS_ES3_ONLY.has(name);
+}
 
 /**
  * Check if the input `node` is a `let` variable declaration.