Could not find a declaration file for module 'webpack' / 'tapable'

[IlCallo]

Current behavior

ERROR in /.../node_modules/fork-ts-checker-webpack-plugin/lib/hooks.d.ts(1,26):
TS7016: Could not find a declaration file for module 'webpack'. '/.../node_modules/webpack/lib/webpack.js' implicitly has an 'any' type.
  Try `npm install @types/webpack` if it exists or add a new declaration (.d.ts) file containing `declare module 'webpack';`
ERROR in /.../node_modules/fork-ts-checker-webpack-plugin/lib/hooks.d.ts(2,43):
TS7016: Could not find a declaration file for module 'tapable'. '/.../node_modules/tapable/lib/index.js' implicitly has an 'any' type.
  Try `npm install @types/tapable` if it exists or add a new declaration (.d.ts) file containing `declare module 'tapable';`
Version: typescript 3.6.3
Time: 5433ms

Expected behavior

No errors by default, or a peerDependencies warning fired off, or a disclaimer in setup section of the README.

Steps to reproduce the issue

Not really sure, I just updated fork-ts-checker-webpack-plugin to 1.5.0 from 0.5.2 and the error popped up.
The error doesn't show up in 1.3.1 because of the typings dependencies being added, then removed again in 1.3.2.
The problematic declaration seems to be into lib/hooks.d.ts, where webpack and tapable are types are imported.

import * as webpack from 'webpack';
import { AsyncSeriesHook, SyncHook } from 'tapable';
export declare type ForkTsCheckerHooks = 'serviceBeforeStart' | 'cancel' | 'serviceStartError' | 'waiting' | 'serviceStart' | 'receive' | 'serviceOutOfMemory' | 'emit' | 'done';
declare type ForkTsCheckerLegacyHookMap = Record<ForkTsCheckerHooks, string>;
export declare const legacyHookMap: ForkTsCheckerLegacyHookMap;
export declare function getForkTsCheckerWebpackPluginHooks(compiler: webpack.Compiler): Record<ForkTsCheckerHooks, SyncHook<any, any, any> | AsyncSeriesHook<any, any, any>>;
export {};

Manually adding the dependencies fix the errors.

Related:

• Could not find a declaration file for module 'webpack' #192
• fix: add @types dependencies for tapable + webpack #281

Environment

• fork-ts-checker-webpack-plugin: 1.5.0
• typescript: 3.6.3
• tslint: N/A
• eslint: 5.10.0
• webpack: 4.41.0
• os: Ubuntu 18.04.3 LTS

[johnnyreilly]

Oh that's a shame. If you'd like to reattempt #281 (I'm not sure how this regressed) I'll certainly take a look at it 🥰

[phryneas]

In #287 I had moved everything depending on webpack/tapable out to hooks.d.ts in the hopes that only index.d.ts would be included automatically and the rest just where used.

We should definitely not add @types/webpack as a dependency, as as I remember that would re-introduce @types/node as a dependency.

Maybe just move the declaration

export declare type ForkTsCheckerHooks = 'serviceBeforeStart' | 'cancel' | 'serviceStartError' | 'waiting' | 'serviceStart' | 'receive' | 'serviceOutOfMemory' | 'emit' | 'done';

to the index.d.ts, reference it from hooks.ts and make sure hooks.d.ts is removed on build, as it won't contain any more external references?

[IlCallo]

If you'd like to reattempt #281

Not sure about how your typings generation works. If @phryneas already have an idea on it, I'll be happy to check if it works.

I think microsoft/TypeScript#18588 is somewhat related and there could be some workarounds. Still, no official solution

[akleiber]

hi @phryneas do you have a PR for this that I may not find? Because you mentioned here #342 (comment) that you are working on it - if not is your suggestion solution the way to go?
-> #339 (comment)

[phryneas]

@akleiber Argh, I had experimented using API-extractor for that, hit a roadblock, got distracted and forgot about that. Sorry!
Yes, comment 339 would be the easy way to go about this. Would you want to do a PR on this? I'm a bit swamped right now.

[piotr-oles]

Fix released in the 5.0.0-alpha.7 version :)