This PR re-includes ESLint with some notable changes, namely a guided setup similar to how TypeScript is instantiated in a Next.js application.
To add ESLint to a project, developers will have to create an `.eslintrc` file in the root of their project or add an empty `eslintConfig` object to their `package.json` file.
```js
touch .eslintrc
```
Then running `next build` will show instructions to install the required packages needed:
<img width="862" alt="Screen Shot 2021-04-19 at 7 38 27 PM" src="https://user-images.githubusercontent.com/12476932/115316182-dfd51b00-a146-11eb-830c-90bad20ed151.png">
Once installed and `next build` is run again, `.eslintrc` will be automatically configured to include the default config:
```json
{
"extends": "next"
}
```
In addition to this change:
- The feature is now under the experimental flag and requires opt-in. After testing and feedback, it will be switched to the top-level namespace and turned on by default.
- A new ESLint shareable configuration package is included that can be extended in any application with `{ extends: 'next' }`
- This default config extends recommended rule sets from [`eslint-plugin-react`](https://www.npmjs.com/package/eslint-plugin-react), [`eslint-plugin-react-hooks`](https://www.npmjs.com/package/eslint-plugin-react-hooks), and [`eslint-plugin-next`](https://www.npmjs.com/package/@next/eslint-plugin-next)
- All rules in [`eslint-plugin-next`](https://www.npmjs.com/package/@next/eslint-plugin-next) have been modified to include actionable links that show more information to help resolve each issue
This pull request **temporarily** removes ESLint, as it was not landed in accordance with our standard experimental policies. We are fully committed to landing this change again.
This is being reverted because:
- Next.js has very strict goals for its install size. This feature resulted in adding over 17MB, or a 43.6% increase.
- The feature was not first landed under the `experimental` key in `next.config.js`, rather, it was added under the stable namespace (top-level)
- Using the feature doesn't do a "guided setup" like TypeScript, it should ask you to "bring your own" dependencies for ESLint
- It uses a undesirable ESLint plugin name: `plugin:@next/next/recommended`. This should read out as strictly `next`, or as short as we can get it.
- Does not provide actionable warnings (missing link to resolve issue)
- Does not follow appropriate console output styling. We need to revisit how these are presented.
To re-land this, we need to ensure the following minimums are met:
- Very minor change in install size
- Fully experimental (i.e. flagged) with warnings
- Finalized package name and configuration shape, preferably so we can do ` { extends: 'next' } `.
For #22228
This PR:
- Adds ESLint to toolchain
- Included by default for builds (`next build`)
- Can be enabled for development (`next dev`)
- Custom formatter built for output
- Adds appropriate tests
- Adds two documentation pages
This pull request ensures the webpack hook is installed before an attempt is made to load the configuration.
This pull request is tested by the PnP tests, which should now be passing as a result of this change.
---
Fixes#21679
**What's the problem this PR addresses?**
`@next/mdx` adds the webpack loader `@mdx-js/loader` without resolving it to an absolute path
Depends on https://github.com/vercel/next.js/pull/17606
**How did you fix it?**
`require.resolve` the webpack loader before adding it
