Ready for review: yarn v2 compat [open discussion]

[AlexandreBonaventure]

Here, the idea is to have a shim of the @typescript-eslint/eslint-plugin so we can keep require statement inside @vue/eslint-config-typescript while keeping it as a peer dependencies.

[AlexandreBonaventure]

This needs typescript-eslint/typescript-eslint#1593 in order to work

[AlexandreBonaventure]

In order to keep the ball moving forward on vuejs/vue-cli#5135
I opened several PRs. Please consider this as a work-in-progress and an open discussion. I'd like to avoid this dirty shimming monkey patch but this is working at least...

Feel free to provide some feedback and contribute

[AlexandreBonaventure]

At the end of the day, it is more a problem to has to do with how eslint loads plugins and the fact that it has not been designed to fit yarn v2 requirements. According to yarnpkg/berry#8 it seems like eslint has shipped some changes to have better support, but I'm not sure yet how it is affecting this issue.

[AlexandreBonaventure]

edit: it actually works like that without the shimming monkey patch

[AlexandreBonaventure]

Here we add vue-eslint-parser as a dependency rather than a peerDependency, otherwise yarn will throw this kind of error

Error: A package is trying to access a peer dependency that should be provided by its direct ancestor but isn't
Required package: vue-eslint-parser (via "vue-eslint-parser")
Required by: @vue/eslint-config-typescript

And it is arguably right to say it has a direct dependency to it anyways

[AlexandreBonaventure]

As demonstrated here: https://github.com/AlexandreBonaventure/workspace-yarn2-example
this patch works, the only breaking change would be that vue-eslint-parser is now added as a direct dependency.

[haoqunjiang]

Makes sense.
It's not a breaking change though. In other configs, vue-eslint-parser is required in the eslint-plugin-vue source code, which has directly depended on it, so previously it's not listed in this package. But now that we want to override the config, we cannot rely on the implict hoisting.

[haoqunjiang]

Actually, for vue-eslint-parser, just adding the dependency should suffice. Because ESLint knows where the parser is required and calls a require function relative to the package directory https://github.com/eslint/eslint/blob/1aa021d77fdd2c68d7b7d2f4603252110c414b32/lib/cli-engine/config-array-factory.js#L888-L906

require.resolve is fine, too, of course.