feat: support multipleConfig

[gaoachao]

Setting Tailwind config path for different entries

multipleConfig can be configured as an object where the key is the entryName and the value is the config path.
If the key cannot be found, it will fallback to config , which is the default config path.

example：

// rspack.config.js
import { TailwindRspackPlugin } from 'rsbuild-plugin-tailwindcss'

export default {
  plugins: [
    new TailwindRspackPlugin({
       multipleConfig: {
         index: './config/tailwind.index.config.js',
         main: './config/tailwind.main.config.js'
       },
    }),
  ],
}

[luhc228]

Can we extend the existing config field to support an object type?

new TailwindRspackPlugin({
    // now is string type
    config: './config.js',
    // object
     config: {
       index: './config/tailwind.index.config.js',
       main: './config/tailwind.main.config.js'
     },
  })

[gaoachao]

@luhc228 Thank you for your suggestion. However, according to our design, multipleConfig is intended to fallback to config, which then fallback to './tailwindcss.config.js'. If we extend config to support object, it would bypass the custom config fallback and directly default to './tailwindcss.config.js', which breaks the intended fallback chain.

[colinaaa]

Honestly, I'm not a fan of the multipleConfig concept. It doesn't feel intuitive to me.

Here are some alternative methods:

1. Support @config directive of Tailwind CSS

This is the best way since it is just how Tailwind CSS works with PostCSS and it does not need extra configuration.

To support @config we need to change processing Tailwind CSS from processAssets to a loader (so that the PostCSS knows about the current file path).

I've implemented a prototype in Tailwind CSS v4, see #17 (comment) for details.

2. Use multiple pluginTailwindCSS

This idea came from the HtmlWebpackPlugin.

export default {
  entry: {
    foo: './src/foo.js',
    bar: './src/bar.js',
  },
  plugins: [
    new TailwindCSSRspackPlugin({
      config: './foo/tailwind.config.js',
      chunks: ['foo.css'],
    }),
    new TailwindCSSRspackPlugin({
      config: './bar/tailwind.config.js',
      chunks: ['bar.css'],
    }),
  ],
}

3. Use config: string | ((entryName: string) => string)