[newfeature]: PostCSS in Angular projects

[leblancmeneses]

In previous discussions, this was closed because Angular was not going to support PostCSS: #9650 .

However, PostCSS custom configuration is now supported in Angular CLI: https://github.com/angular/angular-cli/blob/717d7cbf421f8b56d32739f8bef6dc606d96f387/packages/angular/build/src/utils/postcss-configuration.ts#L20

It would be great if the Nx team could revisit this. angular/angular-cli#27819 .

In an Nx Angular project, I'm able to add the JSON configuration, and it correctly reads a custom plugin I wrote. However, the @nx/angular:setup-tailwind setup does not yet work well with this.

When using a postcss.config.json that looks like:

  "plugins": {
    "tailwindcss": {
      "config": "tailwind.config.js"
    },
    "my-rem-to-em": { }
  }
}

✘ [ERROR] Cannot read properties of undefined (reading 'blocklist') [plugin angular-sass]

    node_modules/.pnpm/[email protected][email protected]_@[email protected]_@[email protected]__@[email protected][email protected]_/node_modules/tailwindcss/lib/lib/setupContextUtils.js:1209:75:
      1209 │ ...fig_blocklist = tailwindConfig.blocklist) !== null && _tailwi...
           ╵                       ```
           
Thanks