Warn on setState

[grossbart]

Version 3.3.0 of ESLint supports warning on setState.

jsx-eslint/eslint-plugin-react#197

[tpreusse]

Not too big of a fan of enabling this – I like saving e.g. calculated layouts in state (on will mount and will update) – stuff that I explicitly don't want to propagate up. Of course I could disable the rule for those dumb components but ESLint rules tend to make you adapt your style and avoid features it doesn't like.

[jstcki]

I'm also against this. This will become even less relevant once React supports pure functions as components (which don't have setState).