switch from babel-eslint to hermes-eslint for flow code

Reviewed By: motiz88

Differential Revision: D37181192

fbshipit-source-id: 1f59e01f306792e67a4977435c5c77e0000d960a

.eslintrc.js

@@ -0,0 +1,72 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+'use strict';
+
+module.exports = {
+  extends: ['fbjs'],
+  parser: 'hermes-eslint',
+  rules: {
+    // Consistency with internal config
+    'no-class-assign': 'off',
+
+    // This is very noisy, so disable
+    'consistent-return': 'off',
+
+    // Flow declares trip up the no-redeclare rule
+    'no-redeclare': 'off',
+
+    // Prettier and ESLint may disagree on the following rules
+    indent: 'off',
+    'array-bracket-spacing': 'off',
+    'comma-dangle': 'off',
+    'max-len': 'off',
+    'space-before-function-paren': 'off',
+    'flowtype/object-type-delimiter': 'off',
+    'babel/flow-object-type': 'off',
+
+    // Tests do not need to follow relay naming rules
+    'relay/graphql-naming': 'off',
+
+    // TODO T31139228: remove or re-enable these once eslint-plugin-flowtype
+    // is compatible with babel-eslint >= 8
+    'no-undef': 'off',
+    'no-unused-vars': 'off',
+
+    // This has a different name internally
+    'no-label-var': 'off',
+
+    // Relay uses console statements for debugging and compile feedback
+    'no-console': [
+      'warn',
+      {
+        allow: [
+          'warn',
+          'error',
+          'debug',
+          'time',
+          'timeEnd',
+          'timeStamp',
+          'groupCollapsed',
+          'groupEnd',
+        ],
+      },
+    ],
+
+    // Duplicating some errors that are enforced internally
+    'prefer-const': 'error',
+    'no-trailing-spaces': 'error',
+
+    // These rules are not required with hermes-eslint
+    'ft-flow/define-flow-type': 0,
+    'ft-flow/use-flow-type': 0,
+    'flowtype/define-flow-type': 0,
+    'flowtype/use-flow-type': 0,
+  },
+};

package.json

@@ -60,6 +60,7 @@
     "gulp-header": "2.0.9",
     "gulp-rename": "^2.0.0",
     "gulp-util": "3.0.8",
+    "hermes-eslint": "0.8.0",
     "invariant": "^2.2.4",
     "jest": "^26.6.3",
     "nullthrows": "^1.1.1",