Use eslint.config.mts (#17573)

JLHwung · nicolo-ribaudo · web-flow · commit c1b55f6ad565 · 2025-10-29T22:26:24.000+01:00
Co-authored-by: Nicolò Ribaudo &lt;hello@nicr.dev&gt;
diff --git a/Makefile.mjs b/Makefile.mjs
diff --git a/Makefile.source.mjs b/Makefile.source.mjs
@@ -355,7 +355,13 @@ target["clone-license"] = function () {
  */
 
 function eslint(...extraArgs) {
-  const eslintArgs = ["--format", "codeframe", ...extraArgs.filter(Boolean)];
+  const eslintArgs = [
+    "--format",
+    "codeframe",
+    "--flag",
+    "unstable_native_nodejs_ts_config",
+    ...extraArgs.filter(Boolean),
+  ];
 
   const packagesPackages = readdirSync("packages").filter(n =>
     existsSync(`packages/${n}/package.json`)
diff --git a/eslint.config.mts b/eslint.config.mts
@@ -1,16 +1,17 @@
-// @ts-check
-
 import babelParser from "@babel/eslint-parser/experimental-worker";
 import globals from "globals";
 import js from "@eslint/js";
+import { defineConfig } from "eslint/config";
 // @ts-expect-error no types
 import pluginImport from "eslint-plugin-import";
 import pluginJest from "eslint-plugin-jest";
 import pluginN from "eslint-plugin-n";
 import configPrettier from "eslint-config-prettier";
 import pluginRegexp from "eslint-plugin-regexp";
 import pluginUnicorn from "eslint-plugin-unicorn";
+// @ts-expect-error no types
 import pluginBabelDevelopment from "@babel/eslint-plugin-development";
+// @ts-expect-error no types
 import pluginBabelDevelopmentInternal from "@babel/eslint-plugin-development-internal";
 import typescriptEslint from "typescript-eslint";
 import { commonJS } from "$repo-utils";
@@ -26,13 +27,13 @@ const testFiles = [
   "codemods/*/test/**/*.js",
   "eslint/*/test/**/*.js",
 ];
-const sourceFiles = exts => [
+const sourceFiles = (exts: string) => [
   `packages/*/src/**/*.{${exts}}`,
   `codemods/*/src/**/*.{${exts}}`,
   `eslint/*/src/**/*.{${exts}}`,
 ];
 
-export default [
+export default defineConfig([
   {
     ignores: [
       "/lib",
@@ -127,11 +128,11 @@ export default [
       "unicorn/prefer-string-starts-ends-with": "error",
     },
   },
-  ...typescriptEslint.config({
-    files: ["**/*.{ts,cts}"],
+  ...defineConfig({
+    files: ["**/*.{ts,cts,mts}"],
     extends: [
-      ...typescriptEslint.configs.recommendedTypeChecked,
-      ...typescriptEslint.configs.stylisticTypeChecked,
+      typescriptEslint.configs.recommendedTypeChecked,
+      typescriptEslint.configs.stylisticTypeChecked,
     ],
     languageOptions: {
       parser: typescriptEslint.parser,
@@ -440,4 +441,4 @@ export default [
       "@typescript-eslint/dot-notation": ["error", { allowKeywords: false }],
     },
   },
-];
+]);
diff --git a/package.json b/package.json
@@ -20,6 +20,7 @@
     "test:runtime:node": "node test/runtime-integration/node.cjs"
   },
   "packageManager": "yarn@4.10.3",
+  "_": "The dependency on minimatch (npm:is-odd@*) is to avoid hoisting of the real minimatch, which causes type issues",
   "devDependencies": {
     "$repo-utils": "link:./scripts/repo-utils",
     "@actions/github": "6.0.1",
@@ -38,7 +39,7 @@
     "@babel/preset-typescript": "8.0.0-beta.0",
     "@babel/runtime": "8.0.0-beta.0",
     "@cspotcode/source-map-support": "^0.8.1",
-    "@eslint/js": "^9.22.0",
+    "@eslint/js": "^9.38.0",
     "@rollup/plugin-babel": "^6.0.4",
     "@rollup/plugin-commonjs": "^25.0.7",
     "@rollup/plugin-json": "^6.1.0",
@@ -52,12 +53,12 @@
     "c8": "^10.0.0",
     "charcodes": "^0.2.0",
     "core-js": "^3.36.1",
-    "eslint": "^9.22.0",
-    "eslint-config-prettier": "^9.1.0",
+    "eslint": "^9.38.0",
+    "eslint-config-prettier": "^10.1.8",
     "eslint-formatter-codeframe": "^7.32.1",
     "eslint-import-resolver-node": "^0.3.9",
     "eslint-plugin-import": "^2.31.0",
-    "eslint-plugin-jest": "^27.9.0",
+    "eslint-plugin-jest": "^29.0.1",
     "eslint-plugin-n": "^17.10.3",
     "eslint-plugin-regexp": "^2.6.0",
     "eslint-plugin-unicorn": "^56.0.0",
@@ -74,6 +75,7 @@
     "json5": "^2.2.3",
     "lint-staged": "^15.2.7",
     "mergeiterator": "^1.4.4",
+    "minimatch": "npm:is-odd@*",
     "picocolors": "^1.0.0",
     "pkg-pr-new": "^0.0.54",
     "prettier": "^3.5.2",
@@ -85,8 +87,8 @@
     "shelljs": "^0.8.5",
     "terser": "^5.43.1",
     "test262-stream": "^1.4.0",
-    "typescript": "5.9.2",
-    "typescript-eslint": "8.39.1"
+    "typescript": "5.9.3",
+    "typescript-eslint": "8.46.2"
   },
   "workspaces": [
     "codemods/*",
@@ -116,7 +118,7 @@
       "git add Makefile.mjs"
     ],
     "*.{js,cjs,mjs,ts,cts,mts}": [
-      "eslint --format=codeframe --cache --cache-strategy=content"
+      "eslint --format=codeframe --cache --cache-strategy=content --flag unstable_native_nodejs_ts_config"
     ],
     "*": [
       "prettier --write --ignore-unknown"
diff --git a/packages/babel-core/src/config/files/index.ts b/packages/babel-core/src/config/files/index.ts
@@ -3,6 +3,7 @@ type indexType = typeof import("./index");
 
 // Kind of gross, but essentially asserting that the exports of this module are the same as the
 // exports of index-browser, since this file may be replaced at bundle time with index-browser.
+// eslint-disable-next-line @typescript-eslint/no-unused-expressions
 ({}) as any as indexBrowserType as indexType;
 
 export { findPackageData } from "./package.ts";
diff --git a/packages/babel-core/src/config/resolve-targets.ts b/packages/babel-core/src/config/resolve-targets.ts
@@ -3,6 +3,7 @@ type nodeType = typeof import("./resolve-targets");
 
 // Kind of gross, but essentially asserting that the exports of this module are the same as the
 // exports of index-browser, since this file may be replaced at bundle time with index-browser.
+// eslint-disable-next-line @typescript-eslint/no-unused-expressions
 ({}) as any as browserType as nodeType;
 
 import type { InputOptions } from "./validation/options.ts";
diff --git a/packages/babel-core/src/transform-file.ts b/packages/babel-core/src/transform-file.ts
@@ -12,6 +12,7 @@ type transformFileType = typeof import("./transform-file");
 // Kind of gross, but essentially asserting that the exports of this module are the same as the
 // exports of transform-file-browser, since this file may be replaced at bundle time with
 // transform-file-browser.
+// eslint-disable-next-line @typescript-eslint/no-unused-expressions
 ({}) as any as transformFileBrowserType as transformFileType;
 
 const transformFileRunner = gensync(function* (
diff --git a/packages/babel-core/test/config-ts-integration-tsx.js b/packages/babel-core/test/config-ts-integration-tsx.js
@@ -27,7 +27,7 @@ const shouldSkip = semver.lt(process.version, "18.0.0");
     let unregister;
     beforeAll(async () => {
       // tsx/cjs/api is a defined sub-export
-      // eslint-disable-next-line import/no-unresolved, import/extensions
+      // eslint-disable-next-line import/extensions
       const tsx = require("tsx/cjs/api");
       // Provide a dummy tsconfig.json to avoid tsx resolving @babel/* from the `src` directory, where
       // undeclared globals such as the PACKAGE_JSON macro will break
diff --git a/packages/babel-generator/src/token-map.ts b/packages/babel-generator/src/token-map.ts
@@ -83,7 +83,7 @@ export class TokenMap {
       // overhead in the simple case of having unique tokens per node.
       if (count > 1) {
         const cache = this._nodesOccurrencesCountCache.get(node);
-        if (cache && cache.test === test && cache.count < count) {
+        if (cache?.test === test && cache.count < count) {
           i = cache.i + 1;
           occurrenceCount -= cache.count + 1;
         }
@@ -143,8 +143,7 @@ export class TokenMap {
     if (
       (node.type === "ExportNamedDeclaration" ||
         node.type === "ExportDefaultDeclaration") &&
-      node.declaration &&
-      node.declaration.type === "ClassDeclaration"
+      node.declaration?.type === "ClassDeclaration"
     ) {
       // Exported class declarations can be not properly nested inside
       // the export declaration that contains them. For example, in
diff --git a/packages/babel-helper-replace-supers/src/index.ts b/packages/babel-helper-replace-supers/src/index.ts
@@ -45,7 +45,7 @@ const unshadowSuperBindingVisitor = visitors.environmentVisitor<{
   Scopable(path, { refName }) {
     // https://github.com/Zzzen/babel/pull/1#pullrequestreview-564833183
     const binding = path.scope.getOwnBinding(refName);
-    if (binding && binding.identifier.name === refName) {
+    if (binding?.identifier.name === refName) {
       path.scope.rename(refName);
     }
   },
diff --git a/packages/babel-helpers/src/helpers/dispose.js b/packages/babel-helpers/src/helpers/dispose.js
@@ -3,7 +3,6 @@
 
 function dispose_SuppressedError(error, suppressed) {
   if (typeof SuppressedError !== "undefined") {
-    // eslint-disable-next-line no-undef
     dispose_SuppressedError = SuppressedError;
   } else {
     dispose_SuppressedError = function SuppressedError(error, suppressed) {
diff --git a/packages/babel-parser/src/plugins/placeholders.ts b/packages/babel-parser/src/plugins/placeholders.ts
@@ -209,7 +209,7 @@ export default (superClass: typeof Parser) =>
       isBreak: boolean,
     ) {
       // @ts-expect-error: node.label could be Placeholder
-      if (node.label && node.label.type === "Placeholder") return;
+      if (node.label?.type === "Placeholder") return;
       super.verifyBreakContinue(node, isBreak);
     }
 
diff --git a/packages/babel-plugin-transform-block-scoping/src/annex-B_3_3.ts b/packages/babel-plugin-transform-block-scoping/src/annex-B_3_3.ts
@@ -95,7 +95,7 @@ const functionsToVarVisitor: Visitor<{ names: string[] }> = {
   Scope(path, { names }) {
     for (const name of names) {
       const binding = path.scope.getOwnBinding(name);
-      if (binding && binding.kind === "hoisted") {
+      if (binding?.kind === "hoisted") {
         maybeTransformBlockScopedFunction(
           binding.path as NodePath<t.FunctionDeclaration>,
         );
diff --git a/packages/babel-plugin-transform-block-scoping/src/index.ts b/packages/babel-plugin-transform-block-scoping/src/index.ts
@@ -165,7 +165,7 @@ const conflictingFunctionsVisitor: Visitor<{ names: string[] }> = {
   Scope(path, { names }) {
     for (const name of names) {
       const binding = path.scope.getOwnBinding(name);
-      if (binding && binding.kind === "hoisted") {
+      if (binding?.kind === "hoisted") {
         path.scope.rename(name);
       }
     }
diff --git a/packages/babel-register/src/worker/transform.cts b/packages/babel-register/src/worker/transform.cts
@@ -117,7 +117,7 @@ function cacheLookup(opts: unknown, filename: string) {
   const cached = cache[cacheKey];
   const fileMtime = +fs.statSync(filename).mtime;
 
-  if (cached && cached.mtime === fileMtime) {
+  if (cached?.mtime === fileMtime) {
     return { cached: cached.value, store: id };
   }
 
diff --git a/packages/babel-traverse/src/path/introspection.ts b/packages/babel-traverse/src/path/introspection.ts
@@ -216,7 +216,7 @@ export function referencesImport(
   }
 
   const binding = this.scope.getBinding((this.node as t.Identifier).name);
-  if (!binding || binding.kind !== "module") return false;
+  if (binding?.kind !== "module") return false;
 
   const path = binding.path;
   const parent = path.parentPath;
diff --git a/packages/babel-types/src/validators/isReferenced.ts b/packages/babel-types/src/validators/isReferenced.ts
@@ -58,7 +58,7 @@ export default function isReferenced(
         return !!parent.computed;
       }
       // parent.value === node
-      return !grandparent || grandparent.type !== "ObjectPattern";
+      return grandparent?.type !== "ObjectPattern";
     // no: class { NODE = value; }
     // yes: class { [NODE] = value; }
     // yes: class { key = NODE; }
diff --git a/packages/babel-types/test/converters.js b/packages/babel-types/test/converters.js
@@ -139,7 +139,6 @@ describe("converters", function () {
       expect(
         t.valueToNode({
           ["__proto__"]: "__proto__",
-          // eslint-disable-next-line no-dupe-keys
           __proto__: null,
         }),
       ).toEqual(
diff --git a/scripts/generators/tsconfig.js b/scripts/generators/tsconfig.js
@@ -380,7 +380,7 @@ maybeWriteFile(
           skipLibCheck: false,
           strict: true,
         },
-        include: ["./lib/libdom-minimal.d.ts", "dts/**/*.d.ts"],
+        include: ["./lib/libdom-minimal.d.ts", "dts/**/*.d.ts", "*.mts"],
         references: Array.from(new Set(projectsFolders.values()))
           .sort()
           .map(path => ({ path })),
diff --git a/tsconfig.json b/tsconfig.json
@@ -10,7 +10,8 @@
   },
   "include": [
     "./lib/libdom-minimal.d.ts",
-    "dts/**/*.d.ts"
+    "dts/**/*.d.ts",
+    "*.mts"
   ],
   "references": [
     {
diff --git a/yarn.config.cjs b/yarn.config.cjs
@@ -354,7 +354,12 @@ function enforceExports({ Yarn }) {
   }
 }
 
-function enforceBabelCodeVersionFor78Compat({ Yarn }, version) {
+/**
+ * Enforces the @babel/core version for compatibility with Babel 7 and 8
+ * @param {Context} context
+ * @param {string} version
+ */
+function enforceBabelCoreVersionFor78Compat({ Yarn }, version) {
   for (const workspace of Yarn.workspaces()) {
     if (workspace.cwd === ".") {
       workspace.set("devDependencies['@babel/core']", version);
@@ -388,7 +393,7 @@ module.exports = {
     enforceRuntimeCorejs2DependsOnCorejs2(ctx);
     enforceBabelHelperBabelDeps(ctx);
     if (process.env.BABEL_CORE_DEV_DEP_VERSION) {
-      enforceBabelCodeVersionFor78Compat(
+      enforceBabelCoreVersionFor78Compat(
         ctx,
         process.env.BABEL_CORE_DEV_DEP_VERSION
       );
diff --git a/yarn.lock b/yarn.lock

Original file line number	Diff line number	Diff line change
`@@ -45,7 +45,7 @@ const unshadowSuperBindingVisitor = visitors.environmentVisitor<{`
`45`	`45`	`Scopable(path, { refName }) {`
`46`	`46`	`// https://github.com/Zzzen/babel/pull/1#pullrequestreview-564833183`
`47`	`47`	`const binding = path.scope.getOwnBinding(refName);`
`48`		`- if (binding && binding.identifier.name === refName) {`
	`48`	`+ if (binding?.identifier.name === refName) {`
`49`	`49`	`path.scope.rename(refName);`
`50`	`50`	`}`
`51`	`51`	`},`