Enforce type checking on babel-{cli,node}

lib/fs-readdir-recursive.d.ts

@@ -0,0 +1,7 @@
+declare module "fs-readdir-recursive" {
+  function read(
+    root: string,
+    filter?: (filename: string, index: number, dir: string) => boolean
+  ): string[];
+  export = read;
+}

lib/kexec.d.ts

@@ -0,0 +1,4 @@
+declare module "kexec" {
+  function execvp(cmd: string, args?: string[]): string;
+  export = execvp;
+}

packages/babel-cli/src/babel/dir.ts

@@ -129,7 +129,7 @@ export default async function ({
   }
 
   let compiledFiles = 0;
-  let startTime = null;
+  let startTime: [number, number] | null = null;
 
   const logSuccess = util.debounce(function () {
     if (startTime === null) {
@@ -178,7 +178,7 @@ export default async function ({
     // when we are sure that all the files have been compiled.
     let processing = 0;
     const { filenames } = cliOptions;
-    let getBase;
+    let getBase: (filename: string) => string | null;
     if (filenames.length === 1) {
       // fast path: If there is only one filenames, we know it must be the base
       const base = filenames[0];

packages/babel-cli/src/babel/file.ts

@@ -8,17 +8,25 @@ import * as util from "./util";
 import type { CmdOptions } from "./options";
 import * as watcher from "./watcher";
 
+import type {
+  SectionedSourceMap,
+  SourceMapInput,
+  TraceMap,
+} from "@jridgewell/trace-mapping";
+
+type Section = SectionedSourceMap["sections"][0];
+
 type CompilationOutput = {
   code: string;
-  map: any;
+  map: SourceMapInput;
 };
 
 export default async function ({
   cliOptions,
   babelOptions,
 }: CmdOptions): Promise<void> {
   function buildResult(fileResults: Array<any>): CompilationOutput {
-    const mapSections = [];
+    const mapSections: Section[] = [];
 
     let code = "";
     let offset = 0;
@@ -70,7 +78,7 @@ export default async function ({
     }
     return count;
   }
-  function emptyMap() {
+  function emptyMap(): Section["map"] {
     return {
       version: 3,
       names: [],
@@ -89,7 +97,10 @@ export default async function ({
       if (babelOptions.sourceMaps && babelOptions.sourceMaps !== "inline") {
         const mapLoc = cliOptions.outFile + ".map";
         result.code = util.addSourceMappingUrl(result.code, mapLoc);
-        fs.writeFileSync(mapLoc, JSON.stringify(encodedMap(result.map)));
+        fs.writeFileSync(
+          mapLoc,
+          JSON.stringify(encodedMap(result.map as TraceMap)),
+        );
       }
 
       fs.writeFileSync(cliOptions.outFile, result.code);
@@ -129,7 +140,7 @@ export default async function ({
   }
 
   async function walk(filenames: Array<string>): Promise<void> {
-    const _filenames = [];
+    const _filenames: string[] = [];
 
     filenames.forEach(function (filename) {
       if (!fs.existsSync(filename)) return;

packages/babel-cli/src/babel/options.ts

@@ -4,6 +4,8 @@ import commander from "commander";
 import { version, DEFAULT_EXTENSIONS } from "@babel/core";
 import glob from "glob";
 
+import type { InputOptions } from "@babel/core";
+
 // Standard Babel input configs.
 commander.option(
   "-f, --filename [filename]",
@@ -179,17 +181,35 @@ commander.usage("[options] <files ...>");
 commander.action(() => {});
 
 export type CmdOptions = {
-  babelOptions: any;
-  cliOptions: any;
+  babelOptions: InputOptions;
+  cliOptions: {
+    filename: string;
+    filenames: string[];
+    extensions: string[];
+    keepFileExtension: boolean;
+    outFileExtension: string;
+    watch: boolean;
+    skipInitialBuild: boolean;
+    outFile: string;
+    outDir: string;
+    relative: boolean;
+    copyFiles: boolean;
+    copyIgnored: boolean;
+    includeDotfiles: boolean;
+    verbose: boolean;
+    quiet: boolean;
+    deleteDirOnStart: boolean;
+    sourceMapTarget: string;
+  };
 };
 
 export default function parseArgv(args: Array<string>): CmdOptions | null {
   //
   commander.parse(args);
 
-  const errors = [];
+  const errors: string[] = [];
 
-  let filenames = commander.args.reduce(function (globbed, input) {
+  let filenames = commander.args.reduce(function (globbed: string[], input) {
     let files = glob.sync(input);
     if (!files.length) files = [input];
     globbed.push(...files);
@@ -264,7 +284,7 @@ export default function parseArgv(args: Array<string>): CmdOptions | null {
 
   const opts = commander.opts();
 
-  const babelOptions = {
+  const babelOptions: InputOptions = {
     presets: opts.presets,
     plugins: opts.plugins,
     rootMode: opts.rootMode,
@@ -303,7 +323,9 @@ export default function parseArgv(args: Array<string>): CmdOptions | null {
   // new options for @babel/core, we'll potentially get option validation errors from
   // @babel/core. To avoid that, we delete undefined options, so @babel/core will only
   // give the error if users actually pass an unsupported CLI option.
-  for (const key of Object.keys(babelOptions)) {
+  for (const key of Object.keys(babelOptions) as Array<
+    keyof typeof babelOptions
+  >) {
     if (babelOptions[key] === undefined) {
       delete babelOptions[key];
     }

packages/babel-cli/src/babel/util.ts

@@ -20,7 +20,7 @@ export function readdir(
   includeDotfiles: boolean,
   filter?: ReaddirFilter,
 ): Array<string> {
-  return readdirRecursive(dirname, (filename, _index, currentDirectory) => {
+  return readdirRecursive(dirname, (filename, index, currentDirectory) => {
     const stat = fs.statSync(path.join(currentDirectory, filename));
 
     if (stat.isDirectory()) return true;
@@ -134,7 +134,7 @@ export function withExtension(filename: string, ext: string = ".js") {
 }
 
 export function debounce(fn: () => void, time: number) {
-  let timer;
+  let timer: NodeJS.Timeout;
   function debounced() {
     clearTimeout(timer);
     timer = setTimeout(fn, time);

packages/babel-cli/src/babel/watcher.ts

@@ -1,11 +1,12 @@
 import { createRequire } from "module";
 import path from "path";
+import type { WatchOptions, FSWatcher } from "chokidar";
 
 const fileToDeps = new Map<string, Set<string>>();
 const depToFiles = new Map<string, Set<string>>();
 
 let isWatchMode = false;
-let watcher;
+let watcher: FSWatcher;
 const watchQueue = new Set<string>();
 let hasStarted = false;
 
@@ -14,15 +15,16 @@ export function enable({ enableGlobbing }: { enableGlobbing: boolean }) {
 
   const { FSWatcher } = requireChokidar();
 
-  watcher = new FSWatcher({
+  const options: WatchOptions = {
     disableGlobbing: !enableGlobbing,
     persistent: true,
     ignoreInitial: true,
     awaitWriteFinish: {
       stabilityThreshold: 50,
       pollInterval: 10,
     },
-  });
+  };
+  watcher = new FSWatcher(options);
 
   watcher.on("unlink", unwatchFile);
 }
@@ -94,33 +96,37 @@ export function updateExternalDependencies(
     Array.from(dependencies, dep => path.resolve(dep)),
   );
 
-  if (fileToDeps.has(absFilename)) {
-    for (const dep of fileToDeps.get(absFilename)) {
+  const deps = fileToDeps.get(absFilename);
+  if (deps) {
+    for (const dep of deps) {
       if (!absDependencies.has(dep)) {
         removeFileDependency(absFilename, dep);
       }
     }
   }
   for (const dep of absDependencies) {
-    if (!depToFiles.has(dep)) {
-      depToFiles.set(dep, new Set());
+    let deps = depToFiles.get(dep);
+    if (!deps) {
+      depToFiles.set(dep, (deps = new Set()));
 
       if (!hasStarted) {
         watchQueue.add(dep);
       } else {
         watcher.add(dep);
       }
     }
-    depToFiles.get(dep).add(absFilename);
+
+    deps.add(absFilename);
   }
 
   fileToDeps.set(absFilename, absDependencies);
 }
 
 function removeFileDependency(filename: string, dep: string) {
-  depToFiles.get(dep).delete(filename);
+  const deps = depToFiles.get(dep) as Set<string>;
+  deps.delete(filename);
 
-  if (depToFiles.get(dep).size === 0) {
+  if (deps.size === 0) {
     depToFiles.delete(dep);
 
     if (!hasStarted) {
@@ -132,16 +138,16 @@ function removeFileDependency(filename: string, dep: string) {
 }
 
 function unwatchFile(filename: string) {
-  if (!fileToDeps.has(filename)) return;
+  const deps = fileToDeps.get(filename);
+  if (!deps) return;
 
-  for (const dep of fileToDeps.get(filename)) {
+  for (const dep of deps) {
     removeFileDependency(filename, dep);
   }
   fileToDeps.delete(filename);
 }
 
 function requireChokidar(): any {
-  // @ts-expect-error - TS is not configured to support import.meta.
   const require = createRequire(import.meta.url);
 
   try {

packages/babel-node/package.json

@@ -37,6 +37,7 @@
     "@babel/core": "workspace:^",
     "@babel/helper-fixtures": "workspace:^",
     "@babel/runtime": "workspace:^",
+    "@types/v8flags": "^3.1.1",
     "fs-readdir-recursive": "^1.0.0",
     "make-dir": "condition:BABEL_8_BREAKING ? : ^2.1.0",
     "rimraf": "^3.0.0"