[5.91.0] "Fixed fs types" breaks outputFileSystem compatibility with memfs

[birdofpreyru]

Bug report

What is the current behavior?

After Webpack upgrade from v5.90.3 to 5.91.0 in an existing project, the TypeScript does not allow the code given in Custom File Systems docs because of typing conflict mismatch:

Type 'IFs' is not assignable to type 'OutputFileSystem'.
  Types of property 'writeFile' are incompatible.
    Type '{ (id: TFileId, data: TData, callback: TCallback<void>): any; (id: TFileId, data: TData, options: string | IWriteFileOptions, callback: TCallback<...>): any; }' is not assignable to type 'WriteFile'.
      Types of parameters 'callback' and 'options' are incompatible.
        Type 'WriteFileOptions' is not assignable to type 'TCallback<void>'.
          Type 'null' is not assignable to type 'TCallback<void>'.ts(2322)
(property) Compiler.outputFileSystem: OutputFileSystem | null

I guess the change for "Fixed fs types" led to a regression.

If the current behavior is a bug, please provide the steps to reproduce.

What is the expected behavior?

Other relevant information:
webpack version:
Node.js version:
Operating System:
Additional tools:

[birdofpreyru]

This is a working workaround:

compiler.outputFileSystem = fs as typeof compiler.outputFileSystem;

[alexander-akait]

Please open an issue in memfs, they have broken fs types, I wrote them, but no feedback, I can't fix it here, sorry

[alexander-akait]

You can make sure to use this:

const fs = require("fs");
const fs1 = require("graceful-fs");

compiler.outputFileSystem = fs;
compiler.outputFileSystem = fs1;

but problems only with memfs, because some methods have wrong types

[alexander-akait]

Anyway feel free to feedback

[birdofpreyru]

I created this issue mostly to make sure you've noticed this problem, and you know that example in Webpack docs does not really work as is now. For my purposes, just forcing the assignment via TypeScript casting is fine, so I don't feel any urge to do anything else about it.

[alexander-akait]

Yeah, memfs works fine with webpack, we have a lot of tests, just the types problem

[michaelfaith]

I just hit this issue as well. It doesn't look like this has been reported in the memfs repo. @birdofpreyru were you planning to file that?

[birdofpreyru]

Nah @michaelfaith , I got distracted by different stuff and never reported it. Please report it there if you have a moment :)