Eslint-plugin-react: Handle new JSX transform

[mrmckeb]

We've added support for the new JSX transform into Create React App (https://github.com/facebook/create-react-app/pull/9645, https://github.com/facebook/create-react-app/pull/9788), and we've been discussing how best to support this in our ESLint config.

I'm not sure if this is a good idea, and wanted some thoughts. I wondered if we should update jsx-uses-react to warn when using a React version that ships with the new transform, and do one of the following:

• Add an autofix (remove all React imports).
• Recommend running the codemod.

For now, we're:

• Auto-detecting support for the new transform (see base.js#L14-L21).
• Updating rules based on that detection, leaving jsx-uses-react on to avoid confusion (see base.js#L52-L58).

[ljharb]

If the jsx-uses-react rule is simply disabled, a “no unused imports” or “no unused variables” rule would already catch an unnecessary React import. When there’s a React version that doesn’t allow the current jsx transform, then the jsx-uses-react rule can be updated to throw an error, but otherwise I’m not sure any change is needed in this plugin.

[mrmckeb]

I was thinking more about explaining why React is no longer needed to be imported.

I agree 100% that you could just rely on a no-unused variable, and as I said I was just interested in thoughts. As the community transitions, some members will obviously be confused... but a change to this plugin may not help, you're right.

We can close this off for now, again I was just interested in thoughts at this stage - thanks for your time!

[cdoublev]

Hello,

It would be nice to detect "runtime": "automatic" for the babel/preset-react option and disable errors from react-in-jsx-scope when applicable, since this rule is recommended.

[ljharb]

I’d rather not couple this plugin to babel so tightly.

[cdoublev]

Obviously. Though I predict that after the release of Babel 8, many people will ask the same thing (or to remove it from recommended rules).

[mrmckeb]

Perhaps the React version detection in this plugin could alter behaviour of the related rule?

[ljharb]

Using React does not guarantee you're using JSX, or Babel, or transpiling at all, so I'm afraid not.