lint: add lint rule which warn unused makeStyles classes

[taisei-13046]

Library

React Components / v9 (@fluentui/react-components)

Describe the feature that you would like added

Currently, I use @fluentui/react-components and style by using makeStyles. This feature proposal is making the new ESLint Rules.

For example.

export const Component = () => {
  const styles = useStyles()
  return (
    <div className={styles.wrapper}>
      <p>hello</p>
    </div>
  )
}

const useStyles = makeStyles({
  wrapper: {},
  // ⚠️ this class should be warned because it's not used
  form: {}
})

This above example means that the makeStyles code should be warned because it has unused styles. Please consider it.

Have you discussed this feature with our team

no

Additional context

no

Validations

• [X] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

Priority

Normal

[Hotell]

fluent v9 core doesn't contain css in js implementation anymore ( we use griffel for css in js ), thus can you please open this issue on griffel repo ?

the rule could be added to eslint-plugin https://github.com/microsoft/griffel/tree/main/packages/eslint-plugin

Last but not least, I'd suggest to add "motivation" behind this rule to provide better motivation. for example: shipping less JS for unused rule definitions etc.

ty!

[layershifter]

FYI I transferred the issue to Griffel repository.

---

This rule could be easily implemented for a case when makeStyles() and useStyles() call are in the same file. However, it's more complicated for a case when useStyles() gets imported from a different file:

import { useStyles } from './x.styles'

function App() {
  const styles = useStyles();
}

I don't think that there is an easy way on how to handle the second case, but I am opened for suggestions.