eslint.config.mjs

// @ts-check

import babelParser from "@babel/eslint-parser/experimental-worker";
import globals from "globals";
import js from "@eslint/js";
// @ts-expect-error no types
import pluginImport from "eslint-plugin-import";
import pluginJest from "eslint-plugin-jest";
import pluginN from "eslint-plugin-n";
import configPrettier from "eslint-config-prettier";
import pluginRegexp from "eslint-plugin-regexp";
import pluginUnicorn from "eslint-plugin-unicorn";
import pluginBabelDevelopment from "@babel/eslint-plugin-development";
import pluginBabelDevelopmentInternal from "@babel/eslint-plugin-development-internal";
import typescriptEslint from "typescript-eslint";
import { commonJS } from "$repo-utils";

const { require } = commonJS(import.meta.url);

const recommendedConfig = js.configs.recommended;

const cjsGlobals = ["__dirname", "__filename", "require", "module", "exports"];

const testFiles = [
  "packages/*/test/**/*.js",
  "codemods/*/test/**/*.js",
  "eslint/*/test/**/*.js",
];
const sourceFiles = exts => [
  `packages/*/src/**/*.{${exts}}`,
  `codemods/*/src/**/*.{${exts}}`,
  `eslint/*/src/**/*.{${exts}}`,
];

export default [
  {
    ignores: [
      "/lib",
      "/build",
      "/.git",
      "package.json",
      "packages/babel-runtime",
      "packages/babel-runtime-corejs2",
      "packages/babel-runtime-corejs3",
      "packages/*/node_modules",
      "packages/*/lib",
      "packages/*/test/fixtures",
      "packages/*/test/tmp",
      "codemods/*/node_modules",
      "codemods/*/lib",
      "codemods/*/test/fixtures",
      "codemods/*/test/tmp",
      "packages/babel-compat-data/build",
      "packages/babel-preset-env/test/debug-fixtures",
      "packages/babel-standalone/babel.js",
      "packages/babel-standalone/babel.min.js",
      "packages/babel-parser/test/expressions",
      "packages/babel-core/src/vendor",
      "eslint/*/lib",
      "eslint/*/node_modules",
      "eslint/*/test/fixtures",
      "scripts/integration-tests/fixtures",
      "test/runtime-integration/*/output.js",
      "test/runtime-integration/*/output-absolute.js",
      "Makefile.js",
      ...(process.env.IS_PUBLISH ? testFiles : []),
    ],
  },
  recommendedConfig,
  pluginRegexp.configs["flat/recommended"],
  {
    languageOptions: {
      parser: babelParser,
      parserOptions: {
        sourceType: "module",
        requireConfigFile: false,
        babelOptions: {
          babelrc: false,
          configFile: false,
          // Todo: Remove the parserOpts here after the proposal gets stage 4.
          parserOpts: {
            plugins: ["importAttributes"],
          },
        },
      },
      globals: {
        ...globals.node,
        ...globals.browser,
      },
    },
    rules: {
      curly: ["error", "multi-line"],
      eqeqeq: ["error", "smart"],
      "linebreak-style": ["error", "unix"],
      "no-case-declarations": "error",
      "no-confusing-arrow": "error",
      "no-empty": ["error", { allowEmptyCatch: true }],
      "no-unused-vars": ["error", { caughtErrors: "none" }],
      "no-var": "error",
      "prefer-const": "error",
    },
  },
  {
    plugins: {
      import: pluginImport,
      n: pluginN,
      unicorn: pluginUnicorn,
      "@babel/development": pluginBabelDevelopment,
      "@babel/development-internal": pluginBabelDevelopmentInternal,
    },
    rules: {
      "n/no-process-exit": "error",
      "import/no-extraneous-dependencies": "error",
      "import/export": "error",
      "regexp/match-any": ["error", { allows: ["[^]", "dotAll"] }],
      "unicorn/prefer-set-has": "error",
      "unicorn/no-typeof-undefined": "error",
      "unicorn/prefer-array-find": "error",
      "unicorn/prefer-array-index-of": "error",
      "unicorn/prefer-includes": "error",
      "unicorn/prefer-string-starts-ends-with": "error",
    },
  },
  ...typescriptEslint.config({
    files: ["**/*.{ts,cts}"],
    extends: [
      ...typescriptEslint.configs.recommendedTypeChecked,
      ...typescriptEslint.configs.stylisticTypeChecked,
    ],
    languageOptions: {
      parser: typescriptEslint.parser,
      parserOptions: {
        allowAutomaticSingleRunInference: true,
        projectService: {
          allowDefaultProject: [
            "packages/babel-helpers/src/helpers/applyDecs2305.ts",
            "scripts/repo-utils/index.d.cts",
            "eslint/babel-eslint-plugin/types.d.cts",
            "eslint/babel-eslint-parser/types.d.cts",
          ],
        },
      },
    },
    plugins: {
      "@typescript-eslint": typescriptEslint.plugin,
    },
    rules: {
      "no-unused-vars": "off",
      "@typescript-eslint/no-unused-vars": [
        "error",
        {
          caughtErrorsIgnorePattern: "^_",
        },
      ],
      "no-dupe-class-members": "off",
      "@typescript-eslint/no-dupe-class-members": "error",
      "no-undef": "off",
      "no-redeclare": "off",
      "@typescript-eslint/ban-ts-comment": [
        "error",
        {
          "ts-ignore": {
            descriptionFormat: "^\\(Babel 7 vs Babel 8\\) .+$",
          },
        },
      ],
      "@typescript-eslint/consistent-type-imports": [
        "error",
        { disallowTypeAnnotations: false },
      ],
      "@typescript-eslint/no-use-before-define": [
        "error",
        {
          functions: false,
          classes: false,
          allowNamedExports: true,
        },
      ],
      "@typescript-eslint/no-confusing-void-expression": [
        "error",
        { ignoreArrowShorthand: true },
      ],
      "@typescript-eslint/no-import-type-side-effects": "error",
      "@typescript-eslint/no-misused-promises": [
        "error",
        {
          checksConditionals: false,
        },
      ],
      "require-await": "off",
      "@typescript-eslint/require-await": "error",

      // Todo: Investigate, for each of these, whether we want them
      "@typescript-eslint/array-type": "off",
      "@typescript-eslint/ban-types": "off",
      "@typescript-eslint/consistent-generic-constructors": "off",
      "@typescript-eslint/consistent-indexed-object-style": "off",
      "@typescript-eslint/consistent-type-definitions": "off",
      "@typescript-eslint/dot-notation": "off",
      "@typescript-eslint/no-base-to-string": "off",
      "@typescript-eslint/no-duplicate-type-constituents": "off",
      "@typescript-eslint/no-empty-function": "off",
      "@typescript-eslint/no-empty-interface": "off",
      "@typescript-eslint/no-explicit-any": "off",
      "@typescript-eslint/no-this-alias": "off",
      "@typescript-eslint/no-unsafe-assignment": "off",
      "@typescript-eslint/no-unsafe-call": "off",
      "@typescript-eslint/no-unsafe-declaration-merging": "off",
      "@typescript-eslint/no-unsafe-member-access": "off",
      "@typescript-eslint/prefer-for-of": "off",
      "@typescript-eslint/prefer-nullish-coalescing": "off",
      "@typescript-eslint/prefer-string-starts-ends-with": "off",
      "@typescript-eslint/restrict-template-expressions": "off",
      "@typescript-eslint/sort-type-constituents": "off",
      "@typescript-eslint/unbound-method": "off",
      "prefer-rest-params": "off",

      // https://github.com/typescript-eslint/typescript-eslint/issues/5014
      "@typescript-eslint/no-inferrable-types": "off",
      "@typescript-eslint/no-unsafe-argument": "off",
      "@typescript-eslint/no-unsafe-return": "off",

      // v8
      "@typescript-eslint/no-require-imports": "off",
      "@typescript-eslint/no-unsafe-function-type": "off",
    },
  }),
  configPrettier,
  {
    files: sourceFiles("js,ts,cjs,mjs"),
    languageOptions: {
      globals: { PACKAGE_JSON: "readonly", USE_ESM: "readonly" },
    },
    rules: {
      "@babel/development/no-undefined-identifier": "error",
      "@babel/development/no-deprecated-clone": "error",
      "guard-for-in": "error",
      "import/extensions": ["error", "ignorePackages"],
      "import/no-unresolved": "error",
    },
  },
  {
    files: sourceFiles("js,ts,cjs,mjs"),
    ignores: [
      // These are bundled
      "packages/babel-parser/**/*.{js,ts}",
      "packages/babel-standalone/**/*.{js,ts}",
    ],
    rules: {
      "import/no-extraneous-dependencies": [
        "error",
        { includeTypes: true, devDependencies: false },
      ],
    },
  },
  {
    files: [
      ...testFiles,
      "packages/babel-helper-transform-fixture-test-runner/src/helpers.{ts,js}",
      "test/**/*.js",
    ],
    ...pluginJest.configs["flat/recommended"],
    rules: {
      ...pluginJest.configs["flat/recommended"].rules,
      "jest/expect-expect": "off",
      "jest/no-standalone-expect": [
        "error",
        {
          additionalTestBlockFunctions: [
            "itBabel7",
            "itBabel7NoESM",
            "itBabel7NodeGte14NoESM",
            "itBabel8",
            "itESLint7",
            "itESLintGte8",
            "itNoESM",
            "itNoWin32",
            "itESM",
            "nodeGte8",
            "nodeGte14",
            "nodeGte12",
            "nodeGte20",
            "nodeGte22_12",
            "nodeLt22_12",
            "nodeGte12NoESM",
            "testFn",
          ],
        },
      ],
      "jest/no-test-callback": "off",
      "jest/valid-describe": "off",
      "import/extensions": ["error", "always"],
      "import/no-extraneous-dependencies": "off",
      "no-restricted-imports": ["error", { patterns: ["**/src/**"] }],
    },
  },
  {
    files: testFiles,
    rules: {
      "n/no-unsupported-features/node-builtins": [
        "error",
        { version: "12.17.0", ignores: ["module"] },
      ],
      "@babel/development-internal/require-default-import-fallback": "error",
      "import/no-unresolved": "error",
    },
  },
  {
    files: [...sourceFiles("js,ts,mjs"), ...testFiles, "test/**/*.js"],
    ignores: [
      // @babel/register is the require() hook, so it will always be CJS-based
      "packages/babel-register/**/*.{js,ts}",
    ],
    rules: {
      "no-restricted-globals": ["error", ...cjsGlobals],
      "no-restricted-imports": [
        "error",
        {
          paths: [
            {
              name: "semver",
              message:
                "semver's named exports are not recognized by the Node.js ESM-CJS interop.",
              importNames: Object.keys(require("semver")).filter(
                // We use it as a type import.
                name => name !== "SemVer"
              ),
            },
          ],
        },
      ],
    },
  },
  {
    files: ["packages/babel-plugin-*/src/index.{js,ts}"],
    ignores: ["packages/babel-plugin-transform-regenerator/**/*.js"],
    rules: {
      "@babel/development/plugin-name": "error",
      eqeqeq: ["error", "always", { null: "ignore" }],
    },
  },
  {
    files: ["packages/babel-helpers/src/helpers/**.{js,ts}"],
    rules: {
      "no-var": "off",
      "comma-dangle": "off",
      "no-func-assign": "off",
      "prefer-spread": "off",
      "import/no-extraneous-dependencies": "off",
      "import/no-unresolved": "off",
      "@typescript-eslint/prefer-optional-chain": "off",
      "unicorn/prefer-includes": "off",
    },
  },
  {
    files: ["packages/babel-traverse/scripts/**/*.js"],
    rules: {
      "import/no-extraneous-dependencies": [
        "error",
        { packageDir: "./packages/babel-traverse" },
      ],
    },
  },
  {
    files: ["packages/babel-plugin-transform-runtime/scripts/**/*.js"],
    rules: {
      "import/no-extraneous-dependencies": [
        "error",
        { packageDir: "./packages/babel-plugin-transform-runtime" },
      ],
    },
  },
  {
    files: ["packages/babel-preset-env/data/**/*.js"],
    rules: {
      "import/no-extraneous-dependencies": [
        "error",
        { packageDir: "./packages/babel-preset-env" },
      ],
    },
  },
  {
    files: ["scripts/**/*.{js,cjs,mjs}"],
    rules: {
      "import/no-extraneous-dependencies": ["error", { packageDir: "." }],
    },
  },
  {
    files: ["packages/babel-parser/typings/babel-parser.d.ts"],
    linterOptions: {
      reportUnusedDisableDirectives: "off",
    },
  },
];