Disable more undesired syntax

package.json

@@ -20,6 +20,7 @@
     "@eslint/eslintrc": "^0.4.0",
     "@lavamoat/allow-scripts": "^2.0.3",
     "@metamask/auto-changelog": "^2.3.0",
+    "@metamask/utils": "^2.1.0",
     "eslint": "^7.23.0",
     "eslint-config-prettier": "^8.1.0",
     "eslint-plugin-import": "^2.22.1",

packages/base/rules-snapshot.json

@@ -293,7 +293,25 @@
   "no-regex-spaces": "error",
   "no-reserved-keys": "off",
   "no-restricted-globals": ["error", "event"],
-  "no-restricted-syntax": ["error", "SequenceExpression"],
+  "no-restricted-syntax": [
+    "error",
+    {
+      "selector": "FunctionExpression",
+      "message": "Function expressions are not allowed"
+    },
+    {
+      "selector": "WithStatement",
+      "message": "With statements are not allowed"
+    },
+    {
+      "selector": "BinaryExpression[operator='in']",
+      "message": "The \"in\" operator is not allowed"
+    },
+    {
+      "selector": "SequenceExpression",
+      "message": "Sequence expressions are not allowed"
+    }
+  ],
   "no-return-assign": ["error", "except-parens"],
   "no-script-url": "error",
   "no-self-assign": "error",

packages/base/src/index.js

@@ -48,9 +48,6 @@ module.exports = {
     curly: ['error', 'all'],
     'no-tabs': 'error',
 
-    // Not required by prettier, but potentially gotchas.
-    'no-restricted-syntax': ['error', 'SequenceExpression'],
-
     /* Core rules */
     'accessor-pairs': 'error',
     'array-callback-return': 'error',
@@ -136,6 +133,27 @@ module.exports = {
     ],
     'no-proto': 'error',
     'no-restricted-globals': ['error', 'event'],
+    'no-restricted-syntax': [
+      'error',
+      {
+        selector: 'FunctionExpression',
+        message: 'Function expressions are not allowed',
+      },
+      {
+        selector: 'WithStatement',
+        message: 'With statements are not allowed',
+      },
+      {
+        selector: `BinaryExpression[operator='in']`,
+        message: 'The "in" operator is not allowed',
+      },
+      // Sequence expressions have potential gotchas with Prettier, and are also
+      // weird!
+      {
+        selector: 'SequenceExpression',
+        message: 'Sequence expressions are not allowed',
+      },
+    ],
     'no-return-assign': ['error', 'except-parens'],
     'no-script-url': 'error',
     'no-self-compare': 'error',

scripts/validate-configs.js

@@ -1,6 +1,7 @@
 const { readdirSync, readFileSync, promises: fs } = require('fs');
 const pathUtils = require('path');
 const { FlatCompat } = require('@eslint/eslintrc');
+const { hasProperty } = require('@metamask/utils');
 const eslintRecommendedConfig = require('eslint/conf/eslint-recommended');
 const {
   configs: { recommended: prettierConfig },
@@ -138,7 +139,7 @@ function validatePrettierRules(
   violations,
 ) {
   prettierRules.forEach((ruleName) => {
-    if (ruleName in flatRules && flatRules[ruleName] !== OFF) {
+    if (hasProperty(flatRules, ruleName) && flatRules[ruleName] !== OFF) {
       violations[packageName].push(ruleName);
     }
   });
@@ -166,7 +167,7 @@ function validateConfigMinimalism(
   Object.entries(config.rules || {}).forEach(([ruleName, ruleValue]) => {
     if (
       deepEqual(flatExtendedRules[ruleName], ruleValue) ||
-      (!(ruleName in flatExtendedRules) && ruleValue === OFF)
+      (!hasProperty(flatExtendedRules, ruleName) && ruleValue === OFF)
     ) {
       violations[packageName].push(ruleName);
     }
@@ -393,7 +394,7 @@ function getRequiredPrettierRules() {
 function getFlatRules(flatConfig, normalizeRules = true) {
   // Flatten the config array into a single object
   const rawFlatRules = flatConfig.reduce((flatRules, config) => {
-    if (RULES in config) {
+    if (hasProperty(config, RULES)) {
       return {
         ...flatRules,
         ...config[RULES],

yarn.lock

@@ -102,6 +102,13 @@
     semver "^7.3.5"
     yargs "^17.0.1"
 
+"@metamask/utils@^2.1.0":
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/@metamask/utils/-/utils-2.1.0.tgz#a65eaa0932b863383844ec323e05e293d8e718ab"
+  integrity sha512-4PHdo5B1ifpw6GbsdlDpp8oqA++rddSmt2pWBHtIGGL2tQMvmfHdaDDSns4JP9iC+AbMogVcUpv5Vt8ow1zsRA==
+  dependencies:
+    fast-deep-equal "^3.1.3"
+
 "@nodelib/fs.scandir@2.1.3":
   version "2.1.3"
   resolved "https://registry.yarnpkg.com/@nodelib/fs.scandir/-/fs.scandir-2.1.3.tgz#3a582bdb53804c6ba6d146579c46e52130cf4a3b"