[New] add support for Flat Config

This change adds support for ESLint's new Flat config system.  It maintains backwards compatibility with `eslintrc`-style configs as well.

To achieve this, we're now dynamically creating flat configs on a new `flatConfigs` export.

Usage

```js
import importPlugin from 'eslint-plugin-import';
import js from '@eslint/js';
import tsParser from '@typescript-eslint/parser';

export default [
  js.configs.recommended,
  importPlugin.flatConfigs.recommended,
  importPlugin.flatConfigs.react,
  importPlugin.flatConfigs.typescript,
  {
    files: ['**/*.{js,mjs,cjs,jsx,mjsx,ts,tsx,mtsx}'],
    languageOptions: {
      parser: tsParser,
      ecmaVersion: 'latest',
      sourceType: 'module',
    },
    ignores: ['eslint.config.js'],
    rules: {
      'no-unused-vars': 'off',
      'import/no-dynamic-require': 'warn',
      'import/no-nodejs-modules': 'warn',
    },
  },
];
```

.editorconfig

@@ -7,3 +7,4 @@ insert_final_newline = true
 indent_style = space
 indent_size = 2
 end_of_line = lf
+quote_type = single

.eslintignore

@@ -7,6 +7,7 @@ tests/files/with-syntax-error
 tests/files/just-json-files/invalid.json
 tests/files/typescript-d-ts/
 resolvers/webpack/test/files
+examples
 # we want to ignore "tests/files" here, but unfortunately doing so would
 # interfere with unit test and fail it for some reason.
 # tests/files

CHANGELOG.md

@@ -10,6 +10,7 @@ This change log adheres to standards from [Keep a CHANGELOG](https://keepachange
 - [`dynamic-import-chunkname`]: add `allowEmpty` option to allow empty leading comments ([#2942], thanks [@JiangWeixian])
 - [`dynamic-import-chunkname`]: Allow empty chunk name when webpackMode: 'eager' is set; add suggestions to remove name in eager mode ([#3004], thanks [@amsardesai])
 - [`no-unused-modules`]: Add `ignoreUnusedTypeExports` option ([#3011], thanks [@silverwind])
+- add support for Flat Config ([#3018], thanks [@michaelfaith])
 
 ### Fixed
 - [`no-extraneous-dependencies`]: allow wrong path ([#3012], thanks [@chabb])
@@ -1125,6 +1126,7 @@ for info on changes for earlier releases.
 
 [#3036]: https://github.com/import-js/eslint-plugin-import/pull/3036
 [#3033]: https://github.com/import-js/eslint-plugin-import/pull/3033
+[#3018]: https://github.com/import-js/eslint-plugin-import/pull/3018
 [#3012]: https://github.com/import-js/eslint-plugin-import/pull/3012
 [#3011]: https://github.com/import-js/eslint-plugin-import/pull/3011
 [#3004]: https://github.com/import-js/eslint-plugin-import/pull/3004
@@ -1874,6 +1876,7 @@ for info on changes for earlier releases.
 [@meowtec]: https://github.com/meowtec
 [@mgwalker]: https://github.com/mgwalker
 [@mhmadhamster]: https://github.com/MhMadHamster
+[@michaelfaith]: https://github.com/michaelfaith
 [@MikeyBeLike]: https://github.com/MikeyBeLike
 [@minervabot]: https://github.com/minervabot
 [@mpint]: https://github.com/mpint

README.md

@@ -106,6 +106,8 @@ The maintainers of `eslint-plugin-import` and thousands of other packages are wo
 npm install eslint-plugin-import --save-dev
 ```
 
+### Config - Legacy (`.eslintrc`)
+
 All rules are off by default. However, you may configure them manually
 in your `.eslintrc.(yml|json|js)`, or extend one of the canned configs:
 
@@ -123,14 +125,41 @@ plugins:
   - import
 
 rules:
-  import/no-unresolved: [2, {commonjs: true, amd: true}]
+  import/no-unresolved: [2, { commonjs: true, amd: true }]
   import/named: 2
   import/namespace: 2
   import/default: 2
   import/export: 2
   # etc...
 ```
 
+### Config - Flat (`eslint.config.js`)
+
+All rules are off by default. However, you may configure them manually
+in your `eslint.config.(js|cjs|mjs)`, or extend one of the canned configs:
+
+```js
+import importPlugin from 'eslint-plugin-import';
+import js from '@eslint/js';
+
+export default [
+  js.configs.recommended,
+  importPlugin.flatConfigs.recommended,
+  {
+    files: ['**/*.{js,mjs,cjs}'],
+    languageOptions: {
+      ecmaVersion: 'latest',
+      sourceType: 'module',
+    },
+    rules: {
+      'no-unused-vars': 'off',
+      'import/no-dynamic-require': 'warn',
+      'import/no-nodejs-modules': 'warn',
+    },
+  },
+];
+```
+
 ## TypeScript
 
 You may use the following snippet or assemble your own config using the granular settings described below it.

config/flat/errors.js

@@ -0,0 +1,14 @@
+/**
+ * unopinionated config. just the things that are necessarily runtime errors
+ * waiting to happen.
+ * @type {Object}
+ */
+module.exports = {
+  rules: {
+    'import/no-unresolved': 2,
+    'import/named': 2,
+    'import/namespace': 2,
+    'import/default': 2,
+    'import/export': 2,
+  },
+};

config/flat/react.js

@@ -0,0 +1,19 @@
+/**
+ * Adds `.jsx` as an extension, and enables JSX parsing.
+ *
+ * Even if _you_ aren't using JSX (or .jsx) directly, if your dependencies
+ * define jsnext:main and have JSX internally, you may run into problems
+ * if you don't enable these settings at the top level.
+ */
+module.exports = {
+  settings: {
+    'import/extensions': ['.js', '.jsx', '.mjs', '.cjs'],
+  },
+  languageOptions: {
+    parserOptions: {
+      ecmaFeatures: {
+        jsx: true,
+      },
+    },
+  },
+};

config/flat/recommended.js

@@ -0,0 +1,26 @@
+/**
+ * The basics.
+ * @type {Object}
+ */
+module.exports = {
+  rules: {
+    // analysis/correctness
+    'import/no-unresolved': 'error',
+    'import/named': 'error',
+    'import/namespace': 'error',
+    'import/default': 'error',
+    'import/export': 'error',
+
+    // red flags (thus, warnings)
+    'import/no-named-as-default': 'warn',
+    'import/no-named-as-default-member': 'warn',
+    'import/no-duplicates': 'warn',
+  },
+
+  // need all these for parsing dependencies (even if _your_ code doesn't need
+  // all of them)
+  languageOptions: {
+    ecmaVersion: 2018,
+    sourceType: 'module',
+  },
+};

config/flat/warnings.js

@@ -0,0 +1,11 @@
+/**
+ * more opinionated config.
+ * @type {Object}
+ */
+module.exports = {
+  rules: {
+    'import/no-named-as-default': 1,
+    'import/no-named-as-default-member': 1,
+    'import/no-duplicates': 1,
+  },
+};

config/react.js

@@ -6,13 +6,11 @@
  * if you don't enable these settings at the top level.
  */
 module.exports = {
-
   settings: {
     'import/extensions': ['.js', '.jsx'],
   },
 
   parserOptions: {
     ecmaFeatures: { jsx: true },
   },
-
 };

config/typescript.js

@@ -9,7 +9,7 @@
 // `.ts`/`.tsx`/`.js`/`.jsx` implementation.
 const typeScriptExtensions = ['.ts', '.cts', '.mts', '.tsx'];
 
-const allExtensions = [...typeScriptExtensions, '.js', '.jsx'];
+const allExtensions = [...typeScriptExtensions, '.js', '.jsx', '.mjs', '.cjs'];
 
 module.exports = {
   settings: {

examples/flat/eslint.config.mjs

@@ -0,0 +1,25 @@
+import importPlugin from 'eslint-plugin-import';
+import js from '@eslint/js';
+import tsParser from '@typescript-eslint/parser';
+
+export default [
+  js.configs.recommended,
+  importPlugin.flatConfigs.recommended,
+  importPlugin.flatConfigs.react,
+  importPlugin.flatConfigs.typescript,
+  {
+    files: ['**/*.{js,mjs,cjs,jsx,mjsx,ts,tsx,mtsx}'],
+    languageOptions: {
+      parser: tsParser,
+      ecmaVersion: 'latest',
+      sourceType: 'module',
+    },
+    ignores: ['eslint.config.mjs', '**/exports-unused.ts'],
+    rules: {
+      'no-unused-vars': 'off',
+      'import/no-dynamic-require': 'warn',
+      'import/no-nodejs-modules': 'warn',
+      'import/no-unused-modules': ['warn', { unusedExports: true }],
+    },
+  },
+];

examples/flat/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "flat",
+  "version": "1.0.0",
+  "main": "index.js",
+  "scripts": {
+    "lint": "cross-env ESLINT_USE_FLAT_CONFIG=true eslint src --report-unused-disable-directives"
+  },
+  "devDependencies": {
+    "@eslint/js": "^9.5.0",
+    "@types/node": "^20.14.5",
+    "@typescript-eslint/parser": "^7.13.1",
+    "cross-env": "^7.0.3",
+    "eslint": "^8.57.0",
+    "eslint-plugin-import": "file:../..",
+    "typescript": "^5.4.5"
+  }
+}

examples/flat/src/exports-unused.ts

@@ -0,0 +1,12 @@
+export type ScalarType = string | number;
+export type ObjType = {
+  a: ScalarType;
+  b: ScalarType;
+};
+
+export const a = 13;
+export const b = 18;
+
+const defaultExport: ObjType = { a, b };
+
+export default defaultExport;

examples/flat/src/exports.ts

@@ -0,0 +1,12 @@
+export type ScalarType = string | number;
+export type ObjType = {
+  a: ScalarType;
+  b: ScalarType;
+};
+
+export const a = 13;
+export const b = 18;
+
+const defaultExport: ObjType = { a, b };
+
+export default defaultExport;

examples/flat/src/imports.ts

@@ -0,0 +1,7 @@
+//import c from './exports';
+import { a, b } from './exports';
+import type { ScalarType, ObjType } from './exports';
+
+import path from 'path';
+import fs from 'node:fs';
+import console from 'console';

examples/flat/src/jsx.tsx

@@ -0,0 +1,3 @@
+const Components = () => {
+  return <></>;
+};

examples/flat/tsconfig.json

@@ -0,0 +1,14 @@
+{
+  "compilerOptions": {
+    "jsx": "react-jsx",
+    "lib": ["ESNext"],
+    "target": "ESNext",
+    "module": "ESNext",
+    "rootDir": "./",
+    "moduleResolution": "Bundler",
+    "esModuleInterop": true,
+    "forceConsistentCasingInFileNames": true,
+    "strict": true,
+    "skipLibCheck": true
+  }
+}

examples/legacy/.eslintrc.cjs

@@ -0,0 +1,24 @@
+module.exports = {
+  root: true,
+  env: { es2022: true },
+  extends: [
+    'eslint:recommended',
+    'plugin:import/recommended',
+    'plugin:import/react',
+    'plugin:import/typescript',
+  ],
+  settings: {},
+  ignorePatterns: ['.eslintrc.cjs', '**/exports-unused.ts'],
+  parser: '@typescript-eslint/parser',
+  parserOptions: {
+    ecmaVersion: 'latest',
+    sourceType: 'module',
+  },
+  plugins: ['import'],
+  rules: {
+    'no-unused-vars': 'off',
+    'import/no-dynamic-require': 'warn',
+    'import/no-nodejs-modules': 'warn',
+    'import/no-unused-modules': ['warn', { unusedExports: true }],
+  },
+};

examples/legacy/package.json

@@ -0,0 +1,16 @@
+{
+  "name": "legacy",
+  "version": "1.0.0",
+  "main": "index.js",
+  "scripts": {
+    "lint": "cross-env ESLINT_USE_FLAT_CONFIG=false eslint src --ext js,jsx,ts,tsx --report-unused-disable-directives"
+  },
+  "devDependencies": {
+    "@types/node": "^20.14.5",
+    "@typescript-eslint/parser": "^7.13.1",
+    "cross-env": "^7.0.3",
+    "eslint": "^8.57.0",
+    "eslint-plugin-import": "file:../..",
+    "typescript": "^5.4.5"
+  }
+}

examples/legacy/src/exports-unused.ts

@@ -0,0 +1,12 @@
+export type ScalarType = string | number;
+export type ObjType = {
+  a: ScalarType;
+  b: ScalarType;
+};
+
+export const a = 13;
+export const b = 18;
+
+const defaultExport: ObjType = { a, b };
+
+export default defaultExport;

examples/legacy/src/exports.ts

@@ -0,0 +1,12 @@
+export type ScalarType = string | number;
+export type ObjType = {
+  a: ScalarType;
+  b: ScalarType;
+};
+
+export const a = 13;
+export const b = 18;
+
+const defaultExport: ObjType = { a, b };
+
+export default defaultExport;

examples/legacy/src/imports.ts

@@ -0,0 +1,7 @@
+//import c from './exports';
+import { a, b } from './exports';
+import type { ScalarType, ObjType } from './exports';
+
+import path from 'path';
+import fs from 'node:fs';
+import console from 'console';

examples/legacy/src/jsx.tsx

@@ -0,0 +1,3 @@
+const Components = () => {
+  return <></>;
+};

examples/legacy/tsconfig.json

@@ -0,0 +1,14 @@
+{
+  "compilerOptions": {
+    "jsx": "react-jsx",
+    "lib": ["ESNext"],
+    "target": "ESNext",
+    "module": "ESNext",
+    "rootDir": "./",
+    "moduleResolution": "Bundler",
+    "esModuleInterop": true,
+    "forceConsistentCasingInFileNames": true,
+    "strict": true,
+    "skipLibCheck": true
+  }
+}

package.json

@@ -31,6 +31,9 @@
     "test": "npm run tests-only",
     "test-compiled": "npm run prepublish && BABEL_ENV=testCompiled mocha --compilers js:babel-register tests/src",
     "test-all": "node --require babel-register ./scripts/testAll",
+    "test-examples": "npm run build && npm run test-example:legacy && npm run test-example:flat",
+    "test-example:legacy": "cd examples/legacy && npm install && npm run lint",
+    "test-example:flat": "cd examples/flat && npm install && npm run lint",
     "prepublishOnly": "safe-publish-latest && npm run build",
     "prepublish": "not-in-publish || npm run prepublishOnly",
     "preupdate:eslint-docs": "npm run build",