Add postcss-use plugin

[Jabher]

And one more thing for today 😅

I think it would be nice to add postcss-use plugin into build pipeline.
I think it will organically fit with package core idea - "zero-configuration". So for current builds nothing will actually change, no new filesystem APIs, no additional keys in CLI, however, the ability to use postcss plugins will suddenly appear.

The thing is that by default it's all same css (OK, with autoprefixer), but you can use @use keyword to add postcss plugins.

@use cssnext;

:root {
    --background: #222;
}

.App-header {
    background-color: var(--background);
}

If that seems ligit, I already have a commit for PR - https://github.com/Jabher/create-react-app/tree/feature/postcss-use.

[gaearon]

I don’t think we want to commit to supporting the PostCSS ecosystem right now. We use autoprefixer as an implementation detail, but we don’t want to lock ourselves into PostCSS yet. Thanks for the suggestion though!

[FezVrasta]

Any updates on this? It would be a great way to enable us to use PostCSS and it would be optional without any additional config.

(well, I'd love a way to define a PostCSS preprocessor... like SugarSS)

[gaearon]

No, there are no updates on this. (Usually if there are updates, they appear on the issue. 😉 )

it would be optional without any additional config.

While it would be “optional”, the reality is that we’d have to keep supporting it forever because some people would rely on it. This could hurt our ability to integrate other (potentially incompatible) tools.

For now our stance is that if you want CSS preprocessors, you should use their command-line utilities to compile the styles down to regular CSS. Then you can import that CSS in your components.

[quantuminformation]

I've pretty much moved all my stylus and less projects over to PostCSS as I see it as the future.

I find that this config is all I need to replicate my Less and Stylus needs:

https://github.com/quantumjs/solar-popup/blob/master/postcss.config.js

Looks like I'll have to stick to css for now, but its good enough.

[joshuarrr]

This could hurt our ability to integrate other (potentially incompatible) tools.

What other tools? Is there something better at post processing css on the horizon? Since postcss is already being used as 'an implementation detail' it seems incomplete to not support other plugins, and a bummer that I would have to had to eject to use them.