[Bug]: CSS support regression

[elsassph]

System Info

  System:
    OS: macOS 14.5
    CPU: (10) arm64 Apple M1 Pro
    Memory: 538.23 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 18.17.1 - ~/.nvm/versions/node/v18.17.1/bin/node
    npm: 9.6.7 - ~/.nvm/versions/node/v18.17.1/bin/npm
    pnpm: 9.4.0 - ~/.nvm/versions/node/v18.17.1/bin/pnpm
    bun: 1.0.15 - ~/.bun/bin/bun
  Browsers:
    Chrome: 126.0.6478.183
    Safari: 17.5
  npmPackages:
    @rspack/cli: 1.0.0-beta.0 => 1.0.0-beta.0 
    @rspack/core: 1.0.0-beta.0 => 1.0.0-beta.0 

Details

Default CSS support doesn't seem to be working, neither by omitting a rule for CSS:

ERROR in ./src/main.css
  × Module parse failed:
  ╰─▶   × JavaScript parsing error: Expected ';', '}' or <eof>
         ╭─[1:1]
       1 │ body {
         ·      ─
       2 │   font-family: Arial, Helvetica, sans-serif;
       3 │   font-size: 20px;
         ╰────

or when setting a default rule with css/auto type:

ERROR in ./src/index.ts
  × No parser registered for 'css/auto'

Reproduce link

https://github.com/elsassph/test-rspack-compat

Reproduce Steps

pnpm run rbuild

[hardfist]

try set experiments.css=true

[chenjiahan]

Ref: https://rspack.dev/blog/announcing-1-0-alpha#bundling-css

[elsassph]

Ugh I guess the note on https://rspack.dev/guide/tech/css wasn't obvious enough...

[chenjiahan]

Yeah, we should improve the guide, I will update it