webpack-dev-middleware/types/index.d.ts requires @types/node@16 when Node.js 12 is still LTS

[octogonz]

Bug report

Suppose a project is trying to maintain compatibility with Node 12 and/or 14:

1. Try to compile webpack-dev-middleware using TypeScript with @types/node version 12.x

Actual Behavior

Encountered 1 errors:
  [typescript] ../../common/temp/node_modules/.pnpm/[email protected][email protected]
  /node_modules/webpack-dev-middleware/types/index.d.ts:204:27 
  - (TS2694) Namespace '"fs"' has no exported member 'StatSyncFn'.

Expected Behavior

Node.js 12 is still LTS, so webpack-dev-middleware should be usable by projects that are trying to maintain support for Node 12 and/or 14.

Suggested solution

The problem is here:

webpack-dev-middleware/types/index.d.ts

type OutputFileSystem = Compiler["outputFileSystem"] & {
  createReadStream?: typeof import("fs").createReadStream;
  statSync?: import("fs").StatSyncFn;  // 👈👈👈
  lstat?: typeof import("fs").lstat;
  readFileSync?: typeof import("fs").readFileSync;
};

The StatSyncFn declaration was newly introduced in @types/node@16:

declare module 'fs' {
    . . .
    export const lstatSync: StatSyncFn;

...whereas in @types/node@14 and before, it looked like this:

declare module 'fs' {
    . . .
    function lstatSync(path: PathLike, options?: StatOptions & { bigint?: false | undefined }): Stats;
    function lstatSync(path: PathLike, options: StatOptions & { bigint: true }): BigIntStats;
    function lstatSync(path: PathLike, options?: StatOptions): Stats | BigIntStats;

So the fix might look like this:

type OutputFileSystem = Compiler["outputFileSystem"] & {
  createReadStream?: typeof import("fs").createReadStream;
  statSync?:  typeof import("fs").lstatSync;  // 👈👈👈
  lstat?: typeof import("fs").lstat;
  readFileSync?: typeof import("fs").readFileSync;
};

Is index.d.ts machine generated?

If so, then maybe webpack-dev-middleware needs to add @types/node@12 to its package.json. The phantom dependency is causing NPM to install the bleeding edge experimental version:

webpack-dev-middleware/package-lock.json

Lines 3304 to 3308 in 4194cd0

	"node_modules/@types/node": {
	"version": "17.0.14",
	"resolved": "https://registry.npmjs.org/@types/node/-/node-17.0.14.tgz",
	"integrity": "sha512-SbjLmERksKOGzWzPNuW7fJM7fk3YXVTFiZWB/Hs99gwhk+/dnrQRPBQjPW9aO+fi1tAffi9PrwFvsmOKmDTyng==",
	"dev": true

[alexander-akait]

PR welcome